coeus_web_fetch

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

With no annotations, the description carries the burden and does disclose SSRF protections and a no-hallucinated-content-on-error guarantee. However, it omits other behavior an agent may need, such as handling of oversized bodies, redirects, or how the optional model/extract_mode parameters affect the analysis.

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 a single sentence with no filler and puts the core fetch/analyze behavior first. The trailing error-behavior clause is relevant and earns its place, though the semicolon construction is slightly dense.

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 and no annotations, so the description must explain both invocation and what the agent will receive. It does not describe return format, the role of model/extract_mode/max_body_size, or how this differs from coeus_web_search, leaving meaningful gaps for a 4-parameter tool.

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%, but the parameter descriptions are mostly labels ('Url', 'Model', 'Extract mode', 'Max body size') and add little meaning. The tool description does not elaborate on these parameters, so it stays at the baseline rather than adding value.

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 a specific verb-resource pair ('Fetch a URL ... and analyze fetched bytes') and adds SSRF protection as a distinguishing trait. It does not explicitly reference siblings like coeus_web_search, so some differentiation is left to inference.

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?

There is no statement of when to choose this tool over alternatives such as coeus_web_search or other analysis tools. The only conditional information ('HTTP failures return error') describes failure behavior, not selection criteria.

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