fetch_url

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

With no annotations, the description must fully disclose behavior. It states the output is clean markdown and hints at content extraction, but fails to mention error handling, timeouts, rate limits, or what happens with inaccessible pages. This is a significant gap for a web-fetching tool.

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 concise sentences, front-loaded with the primary purpose, with no wasted words. Every sentence provides useful information.

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?

The description is adequate for straightforward use cases but lacks details on failure modes, limits, or what constitutes 'clean markdown'. Given no output schema, more context on return value behavior would be helpful for completeness.

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 a baseline of 3 applies. The description adds value by explaining render_js with concrete examples (SPAs, Twitter/X) and clarifying the speed trade-off, which enhances understanding beyond the schema. The extract_content parameter is not elaborated, but overall improvement is notable.

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 states the tool fetches a web page and returns clean markdown, with a specific verb and resource. It hints at differentiation from siblings by mentioning JavaScript-heavy pages, but does not explicitly distinguish from fetch_multiple or screenshot, leaving some ambiguity.

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 provides clear guidance on when to set render_js=true vs false, which is useful for parameter choice. However, it does not address when to use fetch_url over its siblings (fetch_multiple, screenshot, ping, crawl), so cross-tool selection guidance is missing.

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