describe

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false. The description usefully adds that resolution comes from local schemas and that errors return a structured {"error": ...} payload instead of raising, which is behavior beyond the annotations. It does not detail return shape, but that is covered by the output schema.

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 compact and front-loaded: core purpose first, then When to use, Not for, and Behavior. Every sentence carries distinct routing or behavioral information without redundancy.

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?

Given the output schema exists, the description need not explain return values. It covers purpose, usage timing, exclusions, resolution behavior, and error handling, leaving no meaningful gap for an agent selecting or invoking this tool.

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% and the single parameter is fully documented in the schema, including examples and the bare-family-name resolution rule. The description does not add parameter syntax beyond what the schema already provides, so the baseline of 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 states a specific verb and resource: 'Describe a message type: its required fields and input JSON Schema.' It also names the backing source and clearly differentiates itself from siblings by explaining that it feeds 'validate' and 'generate' and is not the tool for raw XML (that is 'parse').

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 explicit usage timing ('After search, to obtain the schema...') and an explicit exclusion ('Not for: Raw XML payloads; parse reads those'). An agent can decide when to call this versus its siblings without inference.

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