fetch_url

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior: redirects are followed automatically and output is converted to readable text versus a raw body. It omits truncation behavior from maxChars, error/timeout handling, and auth requirements, which matters for open-world fetching.

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?

Two tight sentences with no filler; the core behavior is front-loaded and the mode flag is explained immediately after. Every clause earns its place.

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?

There is no output schema, so the description is the only source for return-value expectations; it hints at 'readable text' vs raw body but says nothing about truncation limits or failure modes. Adequate for a simple fetch, but leaves an important gap around maxChars given zero schema coverage.

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%, so the description must carry the semantic load. It explains 'raw' well, but leaves maxChars (default 40000) undocumented — an agent cannot tell whether exceeding it truncates, errors, or paginates — and says nothing about url beyond the obvious.

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?

States a specific verb (fetch) and resource (URL), plus a behavioral detail (follows redirects) and the output shape (readable text). It is clear what the tool does, though it does not explicitly differentiate itself from siblings like browser_navigate or browser_get_text that also retrieve page content.

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 'raw: true' note gives a concrete use case (JSON/APIs) for one mode, which is real usage guidance. However, there is no guidance on when to prefer this over browser_get_text, browser_navigate, or web_search in a large sibling set, leaving the primary routing decision to inference.

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