Lifecycle changedspecification/2025-06-18/basic/lifecycle
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111111```
112112
113113* The client **SHOULD NOT** send requests other than
114 [pings](/specification/2025-06-18/basic/utilities/ping) before the server has responded to the
114 [pings](/specification/2025-06-18/basic/utilities/ping.md) before the server has responded to the
115115 `initialize` request.
116116* The server **SHOULD NOT** send requests other than
117 [pings](/specification/2025-06-18/basic/utilities/ping) and
118 [logging](/specification/2025-06-18/server/utilities/logging) before receiving the `initialized`
117 [pings](/specification/2025-06-18/basic/utilities/ping.md) and
118 [logging](/specification/2025-06-18/server/utilities/logging.md) before receiving the `initialized`
119119 notification.
120120
121121#### Version Negotiation
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134134>
135135> If using HTTP, the client **MUST** include the `MCP-Protocol-Version: <protocol-version>` HTTP header on all subsequent requests to the MCP
136136> server.
137> For details, see [the Protocol Version Header section in Transports](/specification/2025-06-18/basic/transports#protocol-version-header).
137> For details, see [the Protocol Version Header section in Transports](/specification/2025-06-18/basic/transports.md#protocol-version-header).
138138
139139#### Capability Negotiation
140140
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145145
146146| Category | Capability | Description |
147147| - | - | - |
148| Client | `roots` | Ability to provide filesystem [roots](/specification/2025-06-18/client/roots) |
149| Client | `sampling` | Support for LLM [sampling](/specification/2025-06-18/client/sampling) requests |
150| Client | `elicitation` | Support for server [elicitation](/specification/2025-06-18/client/elicitation) requests |
148| Client | `roots` | Ability to provide filesystem [roots](/specification/2025-06-18/client/roots.md) |
149| Client | `sampling` | Support for LLM [sampling](/specification/2025-06-18/client/sampling.md) requests |
150| Client | `elicitation` | Support for server [elicitation](/specification/2025-06-18/client/elicitation.md) requests |
151151| Client | `experimental` | Describes support for non-standard experimental features |
152| Server | `prompts` | Offers [prompt templates](/specification/2025-06-18/server/prompts) |
153| Server | `resources` | Provides readable [resources](/specification/2025-06-18/server/resources) |
154| Server | `tools` | Exposes callable [tools](/specification/2025-06-18/server/tools) |
155| Server | `logging` | Emits structured [log messages](/specification/2025-06-18/server/utilities/logging) |
156| Server | `completions` | Supports argument [autocompletion](/specification/2025-06-18/server/utilities/completion) |
152| Server | `prompts` | Offers [prompt templates](/specification/2025-06-18/server/prompts.md) |
153| Server | `resources` | Provides readable [resources](/specification/2025-06-18/server/resources.md) |
154| Server | `tools` | Exposes callable [tools](/specification/2025-06-18/server/tools.md) |
155| Server | `logging` | Emits structured [log messages](/specification/2025-06-18/server/utilities/logging.md) |
156| Server | `completions` | Supports argument [autocompletion](/specification/2025-06-18/server/utilities/completion.md) |
157157| Server | `experimental` | Describes support for non-standard experimental features |
158158
159159Capability objects can describe sub-capabilities like:
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180180
181181#### stdio
182182
183For the stdio [transport](/specification/2025-06-18/basic/transports), the client **SHOULD** initiate
183For the stdio [transport](/specification/2025-06-18/basic/transports.md), the client **SHOULD** initiate
184184shutdown by:
185185
1861861. First, closing the input stream to the child process (the server)
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193193
194194#### HTTP
195195
196For HTTP [transports](/specification/2025-06-18/basic/transports), shutdown is indicated by closing the
196For HTTP [transports](/specification/2025-06-18/basic/transports.md), shutdown is indicated by closing the
197197associated HTTP connection(s).
198198
199199## Timeouts
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201201Implementations **SHOULD** establish timeouts for all sent requests, to prevent hung
202202connections and resource exhaustion. When the request has not received a success or error
203203response within the timeout period, the sender **SHOULD** issue a [cancellation
204notification](/specification/2025-06-18/basic/utilities/cancellation) for that request and stop waiting for
204notification](/specification/2025-06-18/basic/utilities/cancellation.md) for that request and stop waiting for
205205a response.
206206
207207SDKs and other middleware **SHOULD** allow these timeouts to be configured on a
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208208per-request basis.
209209
210210Implementations **MAY** choose to reset the timeout clock when receiving a [progress
211notification](/specification/2025-06-18/basic/utilities/progress) corresponding to the request, as this
211notification](/specification/2025-06-18/basic/utilities/progress.md) corresponding to the request, as this
212212implies that work is actually happening. However, implementations **SHOULD** always
213213enforce a maximum timeout, regardless of progress notifications, to limit the impact of a
214214misbehaving client or server.
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