One read of Claude Developer Platformapi-20261027T185806Z
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251-260 of 260, page 11 of 11This capture is too large to show at once. Changes 251-260 of 260 are below, significant first; the rest are on the following screens.
cli-sdks-libraries/cli/authentication Changed · +2 / -2 lines
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7373
7474To override the key for a single run, pass [`--api-key-stdin`](https://platform.claude.com/docs/en/cli-sdks-libraries/cli/using#global-flags) and pipe the key to the command. To point at a different API host, set `ANTHROPIC_BASE_URL` or pass `--base-url`.
7575
76If you are using a [personal or service account key](https://platform.claude.com/docs/en/manage-claude/authentication#key-types) that isn't scoped to a workspace, you must [specify the workspace](https://platform.claude.com/docs/en/manage-claude/authentication#select-a-workspace) to run your command in. Do this by setting an `ANTHROPIC_WORKSPACE_ID` environment variable, which the CLI reads automatically, or by using the [`--workspace-id` flag](https://platform.claude.com/docs/en/cli-sdks-libraries/cli/using#global-flags). The value must be a `wrkspc_...` ID.
76If you are using a [personal or service account key](https://platform.claude.com/docs/en/manage-claude/authentication#key-types) that isn’t scoped to a workspace, you must [specify the workspace](https://platform.claude.com/docs/en/manage-claude/authentication#select-a-workspace) to run your command in. Do this by setting an `ANTHROPIC_WORKSPACE_ID` environment variable, which the CLI reads automatically, or by using the [`--workspace-id` flag](https://platform.claude.com/docs/en/cli-sdks-libraries/cli/using#global-flags). The value must be a `wrkspc_...` ID.
7777
7878```bash CLI
7979ant messages create \
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105105 (active) * Workspace wrkspc_01... (Engineering)
106106```
107107
108Read the `(active)` rows to see which credential source and workspace won. The command reports status rather than performing a health check, so don't script against the exit status. For the full ordering of credential sources, see [Credential precedence](https://platform.claude.com/docs/en/manage-claude/wif-reference#credential-precedence).
108Read the `(active)` rows to see which credential source and workspace won. The command reports status rather than performing a health check, so don’t script against the exit status. For the full ordering of credential sources, see [Credential precedence](https://platform.claude.com/docs/en/manage-claude/wif-reference#credential-precedence).
109109
110110## Switch between workspaces
111111
cli-sdks-libraries/middleware Changed · +1 / -1 lines
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171171
172172## Middleware ordering
173173
174When you register multiple middleware, they apply in the order given: the first middleware's "before" code runs first, and its "after" code runs last. Middleware registered on the client runs before middleware passed as a per-request option.
174When you register multiple middleware, they apply in the order given: the first middleware’s “before” code runs first, and its “after” code runs last. Middleware registered on the client runs before middleware passed as a per-request option.
175175
176176In the Go SDK, repeated `option.WithMiddleware` calls concatenate (client first, then method). In the other SDKs, pass an array; later entries wrap inner.
177177
home Changed · +1 / -1 lines
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430430 Deployable starter apps.
431431 </Card>
432432
433 <Card icon="star" title="What's new" href="https://platform.claude.com/docs/en/release-notes/overview">
433 <Card icon="star" title="What’s new" href="https://platform.claude.com/docs/en/release-notes/overview">
434434 Latest features and updates.
435435 </Card>
436436
intro Changed · +1 / -1 lines
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1919
2020## Explore the latest generation of Claude models
2121
22If you're unsure which model to use, start with [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview) for most workloads. Use [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) for demanding reasoning and long-horizon agentic work, or when your evals on Claude Opus 5.5 at higher effort still fall short. All current models support text and image input, text output, multilingual capabilities, vision, and tool use. Each model's page lists the platforms it's available on.
22If you’re unsure which model to use, start with [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview) for most workloads. Use [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) for demanding reasoning and long-horizon agentic work, or when your evals on Claude Opus 5.5 at higher effort still fall short. All current models support text and image input, text output, multilingual capabilities, vision, and tool use. Each model’s page lists the platforms it’s available on.
2323
2424* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (`claude-fable-5-1`) — New — *For demanding reasoning and long-horizon agentic work* — Most capable · Research · Multi-day tasks
2525* [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview) (`claude-opus-5-5`) — New — *For long-running agentic coding and knowledge work* — Complex projects · Agents · Coding
managed-agents/cloud-sandboxes-reference Changed · +1 / -1 lines
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3535| ------------- | ----------------------------------------------------------------------------- |
3636| PostgreSQL 16 | Server and `psql` client are installed. The server is not running by default. |
3737| Redis 7 | Server and `redis-cli` are installed. The server is not running by default. |
38| SQLite | Available through language bindings, such as Python's `sqlite3` module. |
38| SQLite | Available through language bindings, such as Python’s `sqlite3` module. |
3939
4040## Utilities
4141
managed-agents/files Changed · +2 / -2 lines
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1010 betaHeader: managed-agents-2026-04-01
1111---
1212
13You can provide files to your agent by uploading them through the Files API and mounting them in the session's sandbox.
13You can provide files to your agent by uploading them through the Files API and mounting them in the session’s sandbox.
1414
1515## Uploading files
1616
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723723 Files mounted in the sandbox are read-only copies. The agent can read them but cannot modify the original uploaded file. To work with modified versions, the agent writes to new paths within the sandbox.
724724</Note>
725725
726* The path you specify is rooted under the session's uploads directory: a `mount_path` (java, php: `mountPath`; csharp, go: `MountPath`) of `/data.csv` places the file at `/mnt/session/uploads/data.csv` in the sandbox.
726* The path you specify is rooted under the session’s uploads directory: a `mount_path` (java, php: `mountPath`; csharp, go: `MountPath`) of `/data.csv` places the file at `/mnt/session/uploads/data.csv` in the sandbox.
727727* If you omit `mount_path` (java, php: `mountPath`; csharp, go: `MountPath`), the file is placed at `/mnt/session/uploads/<file_id>`.
728728* Parent directories are created automatically.
729729* Paths should be absolute (starting with `/`).
models/fable-5/overview Changed · +1 / -1 lines
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1616
1717## Fable versus Mythos
1818
19[Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) is offered separately for defensive cybersecurity workflows and is available only to organizations verified through Anthropic's verification programs, such as the [Cyber Verification Program](https://support.claude.com/en/articles/14604842). It shares Claude Fable 5's specifications and pricing.
19[Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) is offered separately for defensive cybersecurity workflows and is available only to organizations verified through Anthropic’s verification programs, such as the [Cyber Verification Program](https://support.claude.com/en/articles/14604842). It shares Claude Fable 5’s specifications and pricing.
2020
2121## How it compares to the current lineup
2222
models/haiku-5-5/overview Changed · +1 / -1 lines
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2020
2121For code changes, see the [migration guide](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide). For model IDs, pricing, and limits, see the [Claude Haiku 5.5 overview](https://platform.claude.com/docs/en/models/haiku-5-5/overview). For prompting guidance, see [Prompting Claude Haiku 5.5](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-haiku-5-5).
2222
23[What's new in Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/whats-new-haiku-5-5)
23[What’s new in Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/whats-new-haiku-5-5)
2424
2525## How it compares
2626
models/sonnet-5-5/overview Changed · +2 / -2 lines
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2626
2727One more change alters the response shape without failing any request: [text between tool calls comes back in `thinking` blocks](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5#text-between-tool-calls). An application that streams that text to its users goes quiet between tool calls until it sets a `display` value that returns the text, or turns off up-front thinking with `between_tools`.
2828
29[What's new in Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5)
29[What’s new in Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5)
3030
3131## How it compares
3232
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9696
9797## Good to know
9898
99* Adaptive thinking is on by default. The lowest thinking setting is `between_tools`, which turns off up-front thinking. It works at `high` effort or below. See [What's new in Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5#turn-off-up-front-thinking).
99* Adaptive thinking is on by default. The lowest thinking setting is `between_tools`, which turns off up-front thinking. It works at `high` effort or below. See [What’s new in Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5#turn-off-up-front-thinking).
100100* Setting `temperature`, `top_p`, or `top_k` returns a 400 error.
101101* The minimum cacheable prompt length is 512 tokens. See [Prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#cache-limitations).
102102* On the [Message Batches API](https://platform.claude.com/docs/en/build-with-claude/batch-processing#extended-output-beta), Claude Sonnet 5.5 supports up to 300k output tokens with the `output-300k-2026-03-24` beta header.
release-notes/system-prompts/overview Changed · +1 / -1 lines
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44description: See updates to the core system prompts on [claude.ai](https://claude.ai), the [Claude iOS app](https://anthropic.com/ios), and the [Claude Android app](https://anthropic.com/android).
55---
66
7Claude's web interface ([claude.ai](https://claude.ai)) and mobile apps use a system prompt to provide up-to-date information, such as the current date, to Claude at the start of every conversation. The system prompt also encourages certain behaviors, such as always providing code snippets in Markdown. This prompt is periodically updated to improve Claude's responses. These system prompt updates do not apply to the Claude API. Some models have multiple dated entries on their pages.
7Claude’s web interface ([claude.ai](https://claude.ai)) and mobile apps use a system prompt to provide up-to-date information, such as the current date, to Claude at the start of every conversation. The system prompt also encourages certain behaviors, such as always providing code snippets in Markdown. This prompt is periodically updated to improve Claude’s responses. These system prompt updates do not apply to the Claude API. Some models have multiple dated entries on their pages.
88
99<CardGroup cols={3}>
1010 <Card id="claude-haiku-5-5" title="Claude Haiku 5.5" icon="file" href="https://platform.claude.com/docs/en/release-notes/system-prompts/claude-haiku-5-5" />