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

Annotations already cover the safety profile (readOnly, idempotent, closed-world, non-destructive), so the description's job is to add context. It adds two useful traits: the response carries no personal data, and the counters break down by status alongside per-client and overall limits — behavior an agent would not infer from the annotations alone.

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 sentences, zero filler. The output shape is front-loaded and the usage trigger follows immediately, so an agent scanning the first clause knows what it gets.

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 counter tool with an output schema already present, nothing is missing: purpose, scope exclusion, and the failure condition that motivates a call are all stated. Return-value details are correctly left to the output schema.

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 takes zero parameters, so there is nothing for the description to disambiguate; the baseline of 4 applies. The description correctly does not waste words describing absent inputs.

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?

States a specific verb+resource ('return the number of sighting-report drafts by status and the limits that apply') with grouping (per client and overall) and an explicit exclusion ('no personal data'). This is unambiguous and clearly distinct from the sibling draft_sighting_report and submit_sighting_report, which mutate state.

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?

Gives an explicit trigger for use — 'when draft_sighting_report or submit_sighting_report refused because of a limit' — naming the exact sibling tools that route here. It does not state when not to call it, but the trigger is narrow enough that misuse is unlikely.

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