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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, and the description is consistent with them while adding two things they don't cover: that validation performs no execution, and that provider record text is untrusted data rather than instructions (a prompt-injection guardrail). It still doesn't say what happens when validation fails, but the extra behavioral context is genuine.

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?

Three tight sentences with the core purpose front-loaded, followed by useful scope (target API, docs) and a safety note. Nothing is redundant; the only weakness is that the dense 'registered-schema versus structural coverage' phrasing is compressed past the point of clarity.

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?

An output schema exists, so return values needn't be described, and the annotations cover the safety profile. However, for a six-parameter tool with nested body/query/pathParameters objects and 17% schema coverage, the description leaves too much unexplained — notably what each request part is validated against and what the coverage report contains.

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 only 17% across six parameters, so the description carries the burden and does not meet it: body, query, pathParameters, files, and endpointId are never explained. The phrase 'registered-schema versus structural coverage' hints that endpointId selects a registered operation, but that is an indirect inference, not documentation.

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 ('Validate input') and immediately scopes it with 'without execution', which implicitly separates it from write/execute siblings like system_execute_write. What it returns ('registered-schema versus structural coverage') is also named, though the term 'structural coverage' is never defined, leaving the actual output purpose partly opaque.

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?

Use is only implied: the 'without execution' framing suggests running this as a dry-run check before a write, but no sibling is named (e.g. vs system_prepare_write or system_execute_write) and there are no prerequisites or when-not-to-use conditions. An agent must infer the workflow position from the name alone.

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