ctx_stats

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

With no annotations provided, the description carries the full burden and does so well: it discloses read-only nature, no side effects, the JSON return shape, and the meaning of zero counts as a pending-index signal. This goes beyond the structured data and gives the agent actionable expectations.

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 compact and front-loaded: purpose first, then usage guidance, then a clear sibling alternative. Each sentence contributes distinct value with no repetition or filler.

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 zero-parameter stats tool with no output schema, the description adequately explains what is returned (file/symbol/edge counts and index.db size), how to interpret it (all-zero means not indexed), and what to do next. No critical context is missing.

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 tool has zero parameters, so the schema fully covers everything there is to know. The description adds no parameter-specific detail, but none is needed; this matches the baseline for a no-parameter tool. It instead clarifies output semantics, which is more relevant here.

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 states a specific verb and resource: 'Return index-health statistics as JSON' with precise contents (counts of indexed files, symbols, dependency edges, index.db size). It clearly distinguishes itself from siblings by naming ctx_project as the alternative for broader project overview and implying a separate role from the graph search/impact tools.

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 tells when to use the tool: 'Use to check whether the project has been indexed' and explains the consequence of all-zero counts (must run init/indexing before graph tools work). It also names the alternative for broader overviews (ctx_project), giving clear routing guidance.

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