Fetch several URLs

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description still adds meaningful behavior beyond that: the 12-URL batch cap, per-URL failure isolation ('Failures are reported per URL instead of failing the whole call'), and the concurrent overlap that makes it fast. Remaining gaps are minor, such as the caching behavior behind the refresh param.

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, zero waste. The core capability and return shape are front-loaded, followed by the sibling comparison and then the failure-handling contract, in descending order of importance.

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?

With no output schema, the description carries the return-shape burden and does so adequately by describing per-URL Markdown sections and per-URL error reporting. Behavior is complete enough to invoke correctly, though ordering/pagination semantics and cache behavior are left to the schema.

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%, so the schema already documents urls, format, refresh, max_chars, and concurrency with enums and ranges. The description adds little parameter-level detail beyond echoing the 12-URL cap and Markdown default, so the baseline 3 for schema-driven parameters 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 gives a specific verb (Fetch), a resource (URLs), and a concrete scope: 'up to 12 URLs concurrently', returning 'each as Markdown under its own heading'. It also differentiates itself from the sibling fetch_url by naming it explicitly, so an agent can route between them without opening the schemas.

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?

It states a clear selection condition: 'Cheaper and faster than calling fetch_url repeatedly because the requests overlap', which tells the agent to prefer this tool over the single-URL sibling for batches. There is no explicit when-not guidance (e.g. use web_search when you have no URLs, or fetch_url when you need one page), so it falls short of the top score.

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