Fetch URL

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

Annotations already declare the safety profile (readOnly, idempotent, etc.), but the description adds rich behavioral detail beyond annotations: site-specific extractors for gall.dcinside.com, Clien, Ruliweb, FMKorea, blog.naver.com, namu.wiki, bsky.app, and github.com; handling of non-HTML, PDFs, and binaries; pagination mechanics with start_index and max_length; and error/notice behavior for bot protection and JavaScript-only pages. This is exemplary transparency.

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?

Despite its length, the description is densely packed with essential information and front-loaded with the core action. Every sentence earns its place by covering extraction nuances, content types, pagination, and error cases. There is no filler or redundancy.

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 value details are not needed. The description thoroughly covers the tool's behavior, content handling, pagination, and failure modes. Given the complexity of a web-fetching tool with many site-specific extractors, the description is complete enough for an agent to invoke 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 description coverage is 100%, so the baseline is 3. The description adds meaningful semantics beyond the schema: it explains that raw=true skips extraction and returns decoded response text, and it details the pagination workflow using start_index and max_length with a concrete continuation rule. This goes beyond the schema's brief parameter descriptions.

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 begins with a specific verb and resource: 'Fetch one URL and return its readable content as markdown with a title and metadata.' It clearly distinguishes this tool from the sibling web_search by positioning it as the follow-up for reading full pages. An agent can immediately tell what the tool does and when to choose it over web_search.

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 says to use it after web_search or for any URL the user gives, naming the alternative (web_search) and the condition. However, it does not state when NOT to use fetch (e.g., avoid for binary content or when raw data is needed elsewhere). The context is clear but lacks explicit exclusions.

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