fetch_url

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

No annotations are present, so the description carries the burden of behavior. It discloses the markdown-conversion behavior and hints that JavaScript-heavy pages are not handled, but it does not explicitly state that JavaScript is not executed, nor does it describe truncation via max_chars, error cases, or request-side effects.

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 short sentences, with the core purpose first, usage guidance second, and the conditional fallback last. Every sentence contributes meaningful information with no filler.

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?

For a simple two-parameter fetch tool without an output schema, the description covers purpose, output format, and a key failure mode. It is slightly incomplete around max_chars semantics and does not mention whether the request is static-only, but it is otherwise sufficient.

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 0% and the description adds no parameter-level detail. 'url' is inferable from the first sentence, but 'max_chars' is never explained even though it has a default and likely controls output truncation.

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 starts with a specific verb and resource ('Fetch a web page') and states the output format ('main content as markdown'). It also distinguishes itself from the JavaScript-rendering alternative by targeting 'ordinary pages and articles', making the tool's role clear relative to siblings.

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 when to use the tool ('ordinary pages and articles') and provides a concrete fallback condition ('If the result looks empty or is obviously a JavaScript shell, retry with render_page'). This is direct when/when-not guidance with a named alternative.

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