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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered; the description usefully adds what is actually checked (structure, joint limits, inertia plausibility, collision geometry), which tells the agent how thorough the validation is. It still omits behavior beyond that: how findings are reported, whether validation is strict or heuristic, and whether generation produces a full URDF versus a skeleton. Generation under readOnlyHint is not a contradiction, since it does not mutate external state.

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?

One sentence, front-loaded with the primary verb, and the parenthetical list of check categories earns its space by conveying validation depth. No filler or restated 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?

There is no output schema, so the description carries the burden of explaining what comes back from a validation call — a pass/fail flag, a list of diagnostics with locations, severity levels — and it says nothing about this. It also leaves the mutual exclusivity and required-ness of the two zero-required parameters unexplained. For a tool with two distinct modes and no output schema, these are material gaps.

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 both parameters are already documented as 'Natural-language robot spec' and 'URDF XML to validate'. The description adds only the mode mapping between the two, and it does so implicitly through the example spec rather than stating that exactly one parameter should be provided. Baseline 3 is appropriate.

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 names a specific verb+resource (validate a URDF robot description) and enumerates concrete check categories — structure, joint limits, inertia plausibility, collision geometry — plus a second generation mode. It is clear what the tool does, though the dual purpose sits awkwardly against the tool name 'urdf_validate', which suggests validation only; an agent scanning names might miss the generation capability.

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?

Usage is only implied: the description pairs validation with a URDF and generation with a natural-language spec ('6-DOF arm with parallel gripper'), which hints at which parameter drives which mode. It never states that the two parameters are alternatives, what happens if both or neither are supplied, or any prerequisites. The sibling tools are unrelated domains, so no alternative-routing guidance is needed.

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