Install the PreToolUse hook

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Despite annotations already indicating destructive behavior (destructiveHint:true), the description adds rich context: it writes a PreToolUse hook, merges rather than clobbers, is idempotent, prints exactly what changed, and specifies the exact conditions under which the hook speaks up. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense but every sentence earns its place: it covers purpose, why it's needed, behavior, scope options, and uninstall. It is front-loaded with the main action and flows logically without any fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With only two parameters and no output schema, the description is fully complete. It explains what the tool does, why it's the only way, how it behaves, what it outputs, and all configuration choices. There are no gaps for the agent to guess.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema already covers both parameters fully (100% coverage), but the description adds value by clarifying the default scope and when to use copilot-global vs other scopes. It also reinforces the uninstall parameter's purpose. This goes beyond simple schema repetition.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool installs a PreToolUse hook and explains the specific niche (closing the protocol gap where MCP servers cannot add hooks). It distinguishes this from all sibling tools, which are read/search/save tools, by being the only installation mechanism.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly explains why this tool is needed (the protocol limitation), when to use it (to enforce write discipline), and provides scope choices with defaults and an uninstall option. It gives clear context for selecting copilot-global for VS Code, making the usage guidance strong.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.