fetch_url

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds that the tool supports custom headers and configurable timeout, and implies it returns raw text. No contradictions. Could be improved by mentioning that it returns raw HTTP content and does not modify any state.

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, front-loaded with purpose, and includes an example. Every sentence adds value with no 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?

For a simple fetch tool with 3 parameters (1 required) and 100% schema coverage, the description covers key aspects: what it fetches, when to use, custom headers, timeout. Missing details like response format (implied raw content) but overall adequate.

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 has 100% description coverage (url, headers, timeout all documented). The description adds a concrete example of using auth tokens for headers and shows a usage example, but these add limited value beyond the schema. Baseline 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 states the tool fetches raw HTTP content from a URL (HTML, JSON, XML, plain text) and distinguishes it from sibling tools by positioning it as a first step before extract_text or extract_content. The verb "fetch" and resource "URL" are specific.

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?

Description explicitly says when to use (need raw HTTP content, as first step before certain tools) and notes it's preferred over built-in fetch. However, it lacks explicit 'when not to use' guidance, such as avoiding for structured extraction when extract_structured is better.

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