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fix: keep the last 12 characters of the space ID in the MCP server name - #979
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AWS caps an MCP server name, "_" and a tool name at 64 characters. The name from #968 holds the full space UUID (49 characters), so registration failed for 18 of the 31 allowlisted tools. Keep the first 13 characters of the space ID, and test that every allowlisted tool fits. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The last group of a UUID space ID has no dash, so the name reads as LaunchDarkly-97503e355157. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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October 27, 2026 19:34
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| // mcpServerIDLength is how much of the space ID the server name keeps. AWS | ||
| // caps the name, "_" and a tool name at 64 characters, so a full UUID leaves |
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i'm confused by the 64 vs 12 comment and value
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So 64 is the character limit of a tool name, which is something like <mcp-server-id>_create-flag
The server-id value is LaunchDarkly-<agent-space-id>, where agent-space-id is something like dc00f70b-461c-496c-a320-b3ad0071798d. This PR truncates the <agent-space-id> to the last 12 characters so we get some more space to use in the 64 char limit.
I updated the comment to be a bit clearer hopefully.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
ari-launchdarkly
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Oct 27, 2026
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Related issues
Follow-up to #968, which gave each agent space its own MCP server. That change is unreleased.
Describe the solution you've provided
Setup on a new agent space failed with:
AWS limits the server name,
_and each tool name to 64 characters combined.MCPServerNameForused the full space UUID, which made the name 49 characters, so 18 of the 31 allowlisted tools didn't fit.MCPServerNameFornow keeps the last 12 characters of the space ID, the last group of a UUID, for exampleLaunchDarkly-97503e355157(25 characters). The longest tool,get-experiment-metric-results, now makes a 55-character name.TestMCPServerNameForLeavesRoomForEveryToolchecks every allowlisted tool against the 64-character limit. It fails for 18 tools without this change.Additional context
go test ./internal/awsdevops/...passes.Known gap, for a follow-up PR: a run that failed with this bug already registered a server named
LaunchDarkly-<full space ID>, because AWS checks the length when it associates the server, not when it registers it. After this change, setup no longer finds that server by name, so a rerun registers a new one and leaves the old one in place. The follow-up tags each server with its agent space and removes these leftovers. Until then, deregister the leftover in the AWS console.via LD Research 🤖
🤖 Generated with Claude Code
Note
Overview
Fixes AWS DevOps setup failures where registering MCP tools exceeded the 64-character limit on
serverName_toolName.MCPServerNameFornow uses only the last 12 characters of the agent space ID (the final UUID segment) instead of the full UUID, producing names likeLaunchDarkly-97503e355157so every allowlisted tool fits under the cap.Test support adds
MCPTools()(exported for tests) and new cases that assert the suffix behavior and thatname + "_" + toolstays ≤ 64 for all MCP tools.Reviewed by Cursor Bugbot for commit 987f848. Bugbot is set up for automated code reviews on this repo. Configure here.