Fetch URL

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

The description discloses the retrieval ladder (curl → wget → headless Chrome), the reproduction of user's IP/VPN and User-Agent, and the output transformations for different content types (HTML to Markdown, JSON/text as-is, PDFs/binaries saved to disk). This goes well beyond the readOnlyHint and openWorldHint annotations, providing concrete behavioral context without contradiction.

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 three sentences, tightly structured: first sentence states purpose and key access behavior, second explains the retrieval process and output formats, third gives usage guidance. No redundant words or fluff.

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?

Despite no output schema, the description adequately explains return behavior for different content types, mentions file saving with a reported path, and covers usage context. This is complete for a tool of this complexity.

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?

Input schema coverage is 100%, with detailed descriptions for all four parameters (url, method, cookie_file, timeout_seconds). The tool description adds no additional parameter-level semantics 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 clearly specifies the verb 'Retrieve' and the resource 'a web page or file from the user's own machine', and distinguishes itself from siblings like web-search and fetch-paper by emphasizing arbitrary URL retrieval with the user's access context.

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 explicitly states when to use this tool ('Use this to read sources that a direct client cannot reach') and how it pairs with web search ('pair it with web search'). The method parameter description also advises forcing 'chrome' for JS-heavy or bot-protected pages, giving clear alternative guidance.

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