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customizations-in-the-agent-host

Architecture and hard-won debugging lessons for customization enablement (plugins, MCP servers, agents, skills, instructions) in the agent host. Use when changing how customizations are discovered, published, enabled/disabled, or handed to a provider SDK; when a customization shows the wrong enabled state in the UI; or when a disabled MCP server or plugin is still reaching the model.

Quality

93%

Does it follow best practices?

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SecuritybySnyk

Passed

No findings from the security scan

SKILL.md
Quality
Evals
Security

Quality

Content

96%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

An exemplary knowledge skill: it documents only what Claude cannot infer about this codebase, anchors every rule to named functions and real failure stories, and closes with executable validation. The only structural note is that everything lives inline in one file rather than being split across references.

DimensionReasoningScore

Conciseness

The body is dense with codebase-specific, non-inferable invariants (the overlay base-vs-persistent split, owningPluginUri identity keys, the const-enum type-only-import crash, the test runner not failing on type errors) and contains no explanation of concepts Claude already knows; every section carries unique information with no padding.

5 / 5

Actionability

Guidance is fully concrete: named functions and files (resolveCustomizationEnablement(), targetForMcpServer(), createNoopCustomizationEnablementService()), copy-paste validation commands, a grep-able log signature ("tool_search override … clientMatched=[…]"), and a specific cross-session reproduction recipe.

5 / 5

Workflow Clarity

Sections are sensibly ordered (files to read before changing, mental model, the routing rule, per-provider enforcement traps, debugging playbook, validation), with explicit validation commands, a reproduction recipe, and a known-false-alarms list providing feedback loops for error recovery.

5 / 5

Progressive Disclosure

Well-organized single-file structure with clear section headers and clearly signaled cross-skill pointers (agent-host-logs, launch), but all 126 lines are inline with no content split into bundle files — the under-50-line exception does not apply, and per-provider enforcement minutiae or gotchas could plausibly live in a reference file.

4 / 5

Total

19

/

20

Passed

Description

87%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description that explicitly covers what the skill contains and when to use it, with concrete trigger scenarios that a developer on this codebase would naturally say. The only weaknesses are mild: a slightly flavored noun-phrase opener and a few missing natural synonyms.

DimensionReasoningScore

Specificity

Lists several concrete operations ("discovered, published, enabled/disabled, or handed to a provider SDK") plus two concrete bug scenarios ("wrong enabled state in the UI", "disabled MCP server or plugin is still reaching the model"), but the leading 'what' is a noun-phrase content description ("Architecture and hard-won debugging lessons") with mild flavor rather than pure action verbs — a minor gap versus the comprehensive anchor 5.

4 / 5

Completeness

Explicitly answers both 'what' (architecture and debugging lessons for customization enablement, with the customization types enumerated) and 'when' via a dedicated "Use when" clause with three concrete trigger phrases, matching the top anchor.

5 / 5

Trigger Term Quality

Good keyword coverage with natural audience phrases ("plugins", "MCP servers", "enabled state in the UI", "still reaching the model"), but common synonyms such as "toggle" or "turn on/off" are missing, so it falls just short of comprehensive synonym coverage.

4 / 5

Distinctiveness Conflict Risk

A clearly niched internal domain ("customization enablement ... in the agent host") with distinct, specific triggers like a disabled MCP server still reaching the model — minimal conflict risk with other skills.

5 / 5

Total

18

/

20

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository

microsoft/vscode

Path

.github/skills/customizations-in-the-agent-host/SKILL.md

Reviewed

Table of Contents

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