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

Annotations already declare readOnlyHint and idempotentHint true, so the safety profile is covered. The description adds extra behavioral context: 'Free — does not consume a credit and needs no API key,' which is not in the annotations and is valuable for an agent deciding whether to call it. It also clarifies output content.

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 with no filler. The first sentence states the main purpose and output shape; the second adds cost/auth details. Everything earns its place and the most important info is front-loaded.

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 must convey return structure. It says 'each with its id and the fields it extracts,' giving a reasonable mental model. It could be more explicit about whether the return is an array or object and how fields are structured, but for a simple list tool this is adequate. The zero-parameter complexity lowers the burden.

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 has zero parameters, so there is nothing to clarify. Per the baseline for empty parameter lists this is a 4. The description's mention of output fields (id and extracted fields) is about return values, not parameters, and does not detract.

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 says 'Return the built-in schema templates you can pass to parse_document as schema_id' — a specific verb, resource, and consumer. It also lists examples (invoice, receipt, resume) and distinguishes the output from sibling tools like infer_schema or validate.

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?

The description clearly ties the tool to parse_document's schema_id parameter, implying when to use it: before calling parse_document to know available built-in templates. It does not explicitly say when not to use it or mention infer_schema as an alternative for custom schemas, but the context is strong enough.

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