fetch_page

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

Beyond the readOnlyHint annotation, the description discloses significant behavioral details: stripping navigation/ads/boilerplate, blocking loopback/link-local/cloud-metadata targets, conditional blocking of private targets via FETCH_ALLOW_PRIVATE, and re-validation of redirects at every hop. These are non-obvious behaviors that help the agent understand side effects and constraints.

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 front-loaded with the core purpose in the first sentence, followed by a compact paragraph of essential constraints. Every sentence provides unique value—no fluff or repetition of schema or annotation content.

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?

With a single parameter, a clear output (markdown), and thorough behavioral constraints, the description is complete for an agent to decide when and how to use the tool. The output schema handles return-value details, so the description focuses on input constraints and processing behavior, which it does thoroughly.

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 schema only describes 'url' as 'URL to fetch and extract content from.' The description adds crucial meaning: allowed protocols (http/https), blocked address categories, environment variable effect, and redirect behavior. This goes well beyond the schema's bare parameter description.

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 opens with a specific verb and resource: 'Fetch a web page and extract its content as clean markdown.' This clearly states the tool's function and differentiates it from all sibling tools, which focus on docs, services, and infrastructure data rather than web fetching.

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 implies usage context by stating what the tool fetches (web pages) and includes constraints like 'Only http/https URLs are fetched.' It does not explicitly mention alternatives or when not to use it, but given the entirely different sibling tools, the intended use is clear.

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