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

The annotations already provide readOnlyHint=true and openWorldHint=false, covering the main behavioral safety concern. The description adds the count categories and a sibling pointer, but it does not disclose additional behavioral traits such as data freshness, rate limits, or how 'live/queued/filled' are defined. No contradiction exists.

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?

Two short sentences with the core function front-loaded and a routing pointer after. No wasted or redundant words; every phrase contributes to understanding or usage.

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 stats tool, the description adequately communicates the output categories and routes to a sibling for more detailed status. Some ambiguity remains about what 'book' refers to and the exact meaning of 'live product', but an agent can invoke the tool directly without missing required information.

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 and schema coverage is 100%, so the baseline is 4. The description does not need to explain parameters, and it doesn't.

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 the tool provides counts for three categories (live, queued, filled), which is specific about the resource and output. It also distinguishes itself from the status sibling by pointing to status for the live product. It misses a clear verb like 'returns' or 'fetches', so it doesn't earn a 5.

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 gives an explicit routing hint: 'Use status for the live product.' This indicates a when-not-to-use condition for one alternative. However, it never explicitly states when to use book_stats (e.g., 'when you need aggregate counts'), and the phrase 'live product' is ambiguous, so usage guidance remains mostly implied.

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