feat(mcp): resolve fresh low-level tool ownership

[gesh]

💡 Motivation and Context

Fresh low-level MCP server instances might call a strict tool before they serve tools/list. The SDK then cannot remove its injected arguments before tool validation.

Why: Strict tools must receive only their own arguments. This change follows sdk-specs#98.

💚 How did you test it?

• Ran focused MCP SDK 1.x tests.
• Ran the complete MCP SDK 2.x test suite.
• Ran Ruff, mypy, the public API check, and the import warning check.

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran sampo add to generate a changeset file.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

PostHog Desktop Codex implemented the agreed SDK contract. The implementation keeps unknown ownership fail-open and gives served listings priority over the resolver.

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Created with PostHog Desktop

[github-actions]

posthog-python Compliance Report

Date: 2026-10-08T14:08:01.146911+00:00
Duration: 259833ms

✅ All Tests Passed!

121/121 tests passed

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Capture_V1 Tests

✅ 95/95 tests passed

View Details

Test	Status	Duration
Endpoint And Method.Targets V1 Endpoint	✅	517ms
Endpoint And Method.Does Not Use Legacy Endpoints	✅	511ms
Required Headers.Has Authorization Bearer Header	✅	510ms
Required Headers.Has Content Type Json	✅	511ms
Required Headers.Has Posthog Sdk Info Format	✅	510ms
Required Headers.Has Posthog Attempt Header	✅	510ms
Required Headers.Has Posthog Request Id	✅	510ms
Required Headers.Has Posthog Request Timestamp	✅	510ms
Required Headers.Has User Agent	✅	511ms
Body Format.Body Has Created At And Batch	✅	510ms
Body Format.No Api Key In Body	✅	510ms
Body Format.No Sent At In Body	✅	510ms
Event Format.Event Has Required Root Fields	✅	510ms
Event Format.Event Uuid Is Valid	✅	510ms
Event Format.Event Timestamp Is Rfc3339	✅	510ms
Event Format.Non Utc Event Timestamp Is Converted To Utc	✅	516ms
Event Format.Distinct Id Is String	✅	511ms
Event Format.Distinct Id At Root Not Properties	✅	509ms
Event Format.Custom Properties Preserved	✅	510ms
Event Format.Set Properties Preserved	✅	511ms
Event Format.Set Once Properties Preserved	✅	510ms
Event Format.Groups Properties Preserved	✅	510ms
Event Format.Sdk Generates Uuid If Not Provided	✅	510ms
Event Format.Event Has Required Root Fields Batch	✅	513ms
Event Format.Event Uuid Is Valid Batch	✅	514ms
Event Format.Event Timestamp Is Rfc3339 Batch	✅	513ms
Event Format.Distinct Id Is String Batch	✅	514ms
Event Format.Distinct Id At Root Not Properties Batch	✅	514ms
Event Format.Custom Properties Preserved Batch	✅	513ms
Event Format.Set Properties Preserved Batch	✅	514ms
Event Format.Set Once Properties Preserved Batch	✅	514ms
Event Format.Groups Properties Preserved Batch	✅	513ms
Event Format.Sdk Generates Uuid If Not Provided Batch	✅	514ms
Batch Behavior.Multiple Events In Single Batch	✅	517ms
Batch Behavior.Batch Envelope Smoke	✅	515ms
Batch Behavior.Flush With No Events Sends Nothing	✅	507ms
Batch Behavior.Flush At Triggers Batch	✅	1011ms
Batch Behavior.Created At Reflects Batch Creation Time	✅	511ms
Deduplication.Generates Unique Uuids	✅	517ms
Deduplication.Different Events Same Content Different Uuids	✅	513ms
Deduplication.Preserves Uuid On Retry	✅	6519ms
Deduplication.Preserves Timestamp On Retry	✅	6519ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	6518ms
Deduplication.No Duplicate Events In Batch	✅	518ms
Header Behavior On Retry.Attempt Header Starts At One	✅	511ms
Header Behavior On Retry.Attempt Header Increments On Retry	✅	13520ms
Header Behavior On Retry.Request Id Preserved On Retry	✅	6519ms
Header Behavior On Retry.Different Requests Have Different Request Ids	✅	3020ms
Header Behavior On Retry.Request Timestamp Changes On Retry	✅	6519ms
Response Format Validation.Success Response Has Uuid Keyed Results	✅	511ms
Response Format Validation.Success Response Has Ok For Each Event	✅	514ms
Response Format Validation.Success No Retry After When All Ok	✅	513ms
Response Format Validation.Success Retry After Present When Retry Events	✅	1515ms
Response Format Validation.Success No Retry After When Drop Only	✅	513ms
Response Format Validation.Response Echoes Request Id	✅	509ms
Retry Behavior.Retries On 408	✅	6520ms
Retry Behavior.Retries On 500	✅	6520ms
Retry Behavior.Retries On 503	✅	8518ms
Retry Behavior.Retries On 504	✅	6520ms
Retry Behavior.Retryable Errors Have Retry After	✅	3516ms
Retry Behavior.Respects Retry After On Retryable Error	✅	11517ms
Retry Behavior.Does Not Retry On 400	✅	2514ms
Retry Behavior.Does Not Retry On 401	✅	2512ms
Retry Behavior.Does Not Retry On 402	✅	2514ms
Retry Behavior.Does Not Retry On 413	✅	2511ms
Retry Behavior.Does Not Retry On 415	✅	2514ms
Retry Behavior.Non Retryable Errors Have No Retry After	✅	2513ms
Retry Behavior.Implements Backoff	✅	22525ms
Retry Behavior.Max Retries Respected	✅	22533ms
Partial Batch Handling.Handles 200 Full Success	✅	2511ms
Partial Batch Handling.Handles 200 With All Ok	✅	3515ms
Partial Batch Handling.Does Not Retry Dropped Events	✅	3516ms
Partial Batch Handling.Does Not Retry Limited Events	✅	3516ms
Partial Batch Handling.Prunes Ok Events On Partial Retry	✅	6518ms
Partial Batch Handling.Prunes Dropped Events On Partial Retry	✅	6520ms
Partial Batch Handling.Retries Only Retry Events From Partial	✅	6519ms
Partial Batch Handling.Partial Retry Preserves Uuids	✅	6516ms
Partial Batch Handling.Partial Retry Attempt Header Increments	✅	6521ms
Partial Batch Handling.Partial Retry Request Id Preserved	✅	6520ms
Partial Batch Handling.Respects Retry After On Partial	✅	8521ms
Partial Batch Handling.Unknown Result Treated As Terminal	✅	3514ms
Partial Batch Handling.Mixed Ok Drop Limited No Retry	✅	3518ms
Compression.Sends Gzip Content Encoding	✅	511ms
Compression.No Content Encoding When Disabled	✅	510ms
Compression.Compressed Body Is Decompressible	✅	510ms
Error Handling.Does Not Retry On Unknown 4Xx	✅	2512ms
Event Options.Cookieless Mode Override	✅	511ms
Event Options.Disable Skew Correction Override	✅	510ms
Event Options.Process Person Profile Override	✅	509ms
Event Options.Product Tour Id Override	✅	511ms
Event Options.Unset Options Omitted	✅	510ms
Event Options.Options Override In Batch	✅	513ms
Geoip And Historical Migration.Geoip Disable Injected Into Properties	✅	510ms
Geoip And Historical Migration.Historical Migration Set In Body	✅	509ms
Geoip And Historical Migration.Historical Migration Absent By Default	✅	511ms

Capture_Ai Tests

✅ 5/5 tests passed

View Details

Test	Status	Duration
Routing.Capture Ai Posts To Ai Endpoint	✅	510ms
Routing.Capture Does Not Reroute Ai Named Events	✅	510ms
Identity.Capture Ai Event Has Uuid	✅	510ms
Identity.Capture Ai Keeps Supplied Uuid	✅	510ms
Timestamp Format.Non Utc Event Timestamp Is Converted To Utc	✅	510ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	11ms
Request Payload.Flags Request Uses V2 Query Param	✅	9ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	9ms
Request Payload.Flags Request Omits Authorization Header	✅	9ms
Request Payload.Token In Flags Body Matches Init	✅	9ms
Request Payload.Groups Round Trip	✅	9ms
Request Payload.Groups Default To Empty Object	✅	9ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	9ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	10ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	9ms
Request Lifecycle.No Flags Request On Init Alone	✅	4ms
Request Lifecycle.No Flags Request On Normal Capture	✅	509ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	14ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	9ms
Retry Behavior.Retries Flags On 502	✅	312ms
Retry Behavior.Retries Flags On 504	✅	314ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	511ms

Feature_Flags_Local_Evaluation Tests

✅ 4/4 tests passed

View Details

Test	Status	Duration
Versioned Boolean Matching.Matching Version Missing	✅	70ms
Versioned Boolean Matching.Matching Version 1	✅	71ms
Versioned Boolean Matching.Matching Version 2	✅	69ms
Versioned Boolean Matching.Version Only Reload 1 2 1 2 Missing	✅	34ms

[greptile-apps]

[Medium risk] Adds tool argument ownership tracking for low-level MCP servers.

Fix the $ref ownership mismatch before merging because it disables advertised conversation linking.

_{Reviews (1) · Last reviewed commit: "fix(mcp): preserve listed argument owner..." · Reviewed by Greptile}