memory_stats

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value by specifying the exact data returned (index counts, embedding status, last run) and stating 'Local, read-only, no parameters.' This reinforces and extends the annotation safety profile without contradiction. It doesn't cover edge cases like latency or errors, but for a zero-parameter health check, this is adequate.

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 two sentences: the first front-loads the purpose and returned metrics, the second gives usage context and constraints. Every word earns its place; no fluff or repetition. It is efficiently structured for quick agent parsing.

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, read-only health check, the description is complete. It explains what the tool returns, how to use it, and its relationship to sibling tools. There is no output schema, but the description sufficiently covers the return content. Nothing an agent needs to decide whether to call it 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?

There are zero parameters and the schema is empty, so the baseline is 4. The description explicitly notes 'no parameters,' which is redundant but harmless. Since there is nothing to explain about parameter semantics, the score reflects that the tool needs no further parameter documentation.

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: reporting the health of GigaMail's local mail index, listing specific metrics (indexed threads, messages, senders, embedding status, last run). It distinguishes itself from search_mail and sender_history by explicitly framing itself as a health check for those tools, making its role unambiguous.

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 gives a specific use case: 'Use it to know whether search_mail's local_index and sender_history can return anything.' This is clear context for when to call the tool. It doesn't explicitly list alternative tools or when not to use it, but the reference to search_mail and sender_history implies the decision point. Slightly more explicit exclusions would earn a 5, but it's strong.

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