web_fetch

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

With no annotations, the description carries the full burden and does well: it discloses the return payload (title + Markdown body) and the three failure modes (unreachable, site-blocked, no extractable body). It stops short of covering auth needs, rate limits, or truncation/redirect behavior.

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 short sentences, front-loaded with purpose, then usage, then failure modes; none of it is filler and each sentence changes how an agent would call it.

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?

Output schema exists so return values need not be spelled out, and failure modes plus the search-to-fetch workflow are covered. Minor gaps remain around dynamic pages, truncation, and redirects for a fetch 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 coverage is 100% and the url parameter is already fully documented there (absolute http/https, length cap, no credentials), so baseline is 3. The description adds only the contextual hint that the url typically comes from web_search, not new format semantics.

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?

States a specific verb and resource ("Fetch one web page") plus the return shape (title and Markdown body), which cleanly separates it from web_search's summarized results. An agent can identify the tool without reading the schema.

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?

Explicitly routes the agent: use it on a url returned by web_search when the summary is not enough, naming the sibling and the condition that selects this tool. The escalation path from search to fetch is unambiguous.

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