codebase_index

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

The description discloses asynchronous behavior (returns immediately, background indexing) and idempotency if already indexing. No annotations exist, so it carries full burden. Could mention resource impact, but sufficient for typical use.

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 sentences, each earning its place: action, async behavior, post-indexing steps, and edge case. No redundancy, front-loaded with the core purpose.

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?

For a tool with 0 required parameters, no output schema, and no annotations, the description covers what the tool does, how it behaves, and how to monitor progress. Missing details on progress format, but overall 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?

Input schema has 100% description coverage for both parameters. The description adds minimal value beyond schema; it restates the default behavior for projectPath and the purpose of extraExtensions. Baseline 3 is appropriate.

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 initiates background indexing, distinguishes itself by referencing codebase_status for polling, and warns against searching prematurely. It's specific and actionable.

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?

Explicitly tells when to use (start indexing), how to proceed after (poll with codebase_status), and what not to do (do not search until complete). Also handles the edge case of already indexing.

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