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

Beyond the readOnly/idempotent/openWorld annotations, it discloses the ±12 minute matching window, the temporal limits, the excluded object families, and the crucial epistemic caveat that a match means 'compatible with the observation, not proven' and that the tool never asserts 'UFO detected'. That caveat directly shapes how an agent should relay results.

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?

Purpose is front-loaded in the opening clause, followed by routing, scope limits, and the caveat in descending priority. It is dense but every clause carries distinct information — no restatement of the name or title.

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 7-parameter, open-world candidate-ranking tool with an output schema already covering return values, the description supplies everything an agent needs: what it compares, when to prefer it, its temporal window, its blind spots, and how to interpret a match.

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 100%, so parameters like lat/lng/time/az/moving are already fully documented, establishing a baseline of 3. The description adds only mild framing — that az/elevation precision is what separates this tool from identify — and does not add format or alias guidance beyond the schema (e.g. lon/lng aliasing is schema-only).

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 and resource ('Explain a light someone saw') and immediately enumerates the comparison set — ISS, Tiangong, ~160 bright satellites, planets, Moon, bright stars — plus the ranking behavior. It explicitly names the siblings it is not (identify, which_star), so an agent can route without opening any schema.

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 selection rule: 'Use it for an imprecise memory; with a measured azimuth and elevation use identify, for a steady point use which_star.' It also bounds the applicable regime (up to 10 days back, 2 days ahead) and lists what is out of scope (aircraft, drones, lanterns, meteors).

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