Fetch data from a URL

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

No annotations are provided, so the description carries full burden. It discloses return behavior: text formats return content, large responses are truncated, binary returns metadata only. This goes beyond a simple 'fetch' description. However, it omits authentication needs, rate limits, or error handling specifics.

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 sentences, no redundant information. The description is front-loaded with the key action and resource, then adds return behavior and usage guidance. Every sentence 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?

Given the tool's simplicity (2 params, no output schema), the description covers main scenarios: what URLs to use, what is returned for text vs binary, and size limits. It does not cover edge cases like invalid URLs or authentication, but for a straightforward fetch tool it is sufficiently complete.

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% and both parameters have descriptions in the schema. The description adds context about maxKilobytes (truncation behavior) and mentions text formats, which relates to the url parameter's effect. This provides slight additional meaning beyond the schema.

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 downloads data from specific URL types (downloadURL, accessURL, API endpoint, etc.) and contrasts it with sibling tools by noting it retrieves the data itself, not catalogue metadata. The verb 'download' with resource 'data' is specific and 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 explains when to use this tool (after obtaining a data URL from get_dataset or get_api) and implicitly when not to (for metadata). It names alternatives (get_dataset, get_api) but does not explicitly state exclusions like 'do not use for catalogue lookups.'

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