codebase_index

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

Discloses background execution, immediate return, and progress on re-index. No annotations exist, so description carries full burden; lacks details on cancellation or idempotency but sufficient for core behavior.

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?

Three succinct sentences with no redundancy; front-loaded with primary action and structured logically (action, return, post-conditions, edge case).

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?

Given no output schema and a background workflow, description fully covers the interaction pattern (start, poll, wait), prerequisites, and alternative tools, making it complete for agent usage.

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?

With 100% schema coverage, description adds valuable context: absolute path for projectPath, comma-separated format and env var fallback for extraExtensions, exceeding schema info.

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?

Clearly states verb+resource ('Start indexing a codebase') and distinguishes from siblings like codebase_status and codebase_search by specifying the background nature and return behavior.

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?

Provides explicit when-to-use and when-not: poll with codebase_status, do not search until complete, and handles the 'already indexing' case.

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