Read a documentation page

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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld. The description adds crucial behavioral context beyond annotations: URL safety re-checking on every redirect, refusal of private/loopback/metadata addresses, and a prompt-injection warning treating content as evidence not instructions. This is valuable context not covered by annotations.

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 dense sentences with no wasted words. Information is front-loaded with the core operation, then parameters, then the reader mode, then security constraints. The security note is somewhat abrupt but earns its place.

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 4 parameters, no output schema, and rich annotations, the description covers the essential behavioral traits: pagination windowing, content type handling, JS rendering fallback, and URL safety. It could mention error handling or rate limits but is largely complete for an agent to call it correctly.

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 coverage is 0%, so the description must compensate. It explains offset and max_chars as windowing controls and reader as a fetch mode for JS-rendered pages. The url parameter is self-evident. However, it doesn't clarify default values or units for offset/max_chars beyond what the schema implies.

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 (fetch) and resource (one API documentation page), specifies supported formats, and clarifies exactly what is returned (readable text, title, links). Clearly distinguished from siblings like catalog_get or ingest_openapi by its page-fetching purpose.

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?

Explicitly states when to use reader: true (JS-rendered pages or 403 responses), which is a clear conditional usage guideline. However, it doesn't state when to prefer this tool over alternatives like catalog_get for documentation lookup.

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