webfetch

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

Even though no annotations are provided, the description states 'This tool is read-only,' which is a critical safety trait. It also discloses that format controls the output type and the default behavior (Markdown). This provides meaningful behavioral context beyond the schema.

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 sentences, front-loaded with the core purpose, followed by the key format detail and read-only safety note. Every word earns its place with no unnecessary 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 fetch tool with 3 parameters and no output schema, the description adequately explains what the tool returns (formatted content) and its read-only nature. It doesn't cover error handling or redirects, but these are not essential for a basic fetch operation.

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 coverage is 100%, so the baseline is 3. The description mentions 'format' and its default, but this is redundant with the schema description. It adds no additional meaning beyond what the schema already provides for url or timeout.

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 uses the specific verb 'Fetch content' and clearly identifies the resource as 'a fully formed HTTP or HTTPS URL'. This distinguishes it from sibling tools like 'read' (file reading) and 'websearch' (web search), making the purpose unambiguous.

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 implies clear usage: use it when you have a complete HTTP/HTTPS URL. It also restricts to fully formed URLs, excluding relative or non-HTTP URLs. However, it does not explicitly mention alternatives or when not to use the tool, so it doesn't earn a 5.

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