index

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

With no annotations provided, the description carries full burden and does well by explaining the three modes and their behaviors ('incremental' for new/changed, 'full' for delete and rebuild, 'cancel' to stop). It could mention performance impact or permissions but covers core operational traits.

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 with zero waste: first states purpose, second gives usage guidelines, third details modes. Each sentence earns its place, and the structure is front-loaded with essential information.

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 3 parameters, no annotations, and no output schema, the description is quite complete—covering purpose, usage, and key parameter semantics. It could note that 'full' mode might be resource-intensive or that 'confirm' is for safety, but it's largely adequate.

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 description coverage is 0%, so the description must compensate. It explains the 'mode' parameter's three values and their meanings, which adds crucial semantics beyond the bare enum in the schema. It doesn't cover 'project' or 'confirm', but the mode explanation is substantial.

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 purpose with specific verbs ('Update the search index') and resources ('recent Claude Code sessions'), distinguishing it from sibling tools like 'search' or 'list_sessions' which query rather than update the index.

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?

Explicit guidance is provided on when to use this tool: 'if search returns stale results or the user asks to refresh the index.' This directly addresses the tool's purpose relative to alternatives like 'search'.

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