Index / refresh the repository

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

Beyond the annotations (idempotentHint=true, destructiveHint=false), the description adds meaningful behavioral details: incremental re-parsing based on mtime changes, honoring a config file (.slimdex.json), and reporting config problems instead of silently ignoring them. This provides valuable context for the agent about side effects and error 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?

The description is three sentences, front-loaded with the primary purpose, followed by usage guidance and config behavior. Every sentence adds distinct value: purpose, re-run guidance, and config handling. No fluff or redundancy.

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?

The tool is simple (one optional parameter, no output schema) and the description covers its purpose, usage timing, incremental behavior, and config handling. It does not explicitly describe return values, but the lack of an output schema and the emphasis on side effects make the description sufficiently complete for an agent to use it correctly.

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?

The schema description covers the only parameter (force) 100%, so the schema fully explains the parameter. The tool description does not add any parameter-specific meaning, but the behavior it describes (mtime-based caching) indirectly relates to force. With full schema coverage, no extra info in the description is needed.

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's function: 'Build or refresh the persistent code index (symbols + imports)'. This uses a specific verb ('build'/'refresh') with a specific resource ('persistent code index') and differentiates it from sibling search tools like search_code and find_definition by focusing on index maintenance rather than querying.

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?

The description provides clear context on when to use the tool: 're-run it liberally, like git fetch, before trusting a search'. This implies it is a prerequisite for reliable search results. It does not explicitly mention alternatives or exclusions, but the usage context is clear enough.

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