Web Fetch

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive behavior, but the description adds operationally meaningful context not in the annotations: robots.txt compliance and a per-domain rate limit. It omits what happens on rate-limit violation or fetch failure, so it is not fully transparent.

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 compact, front-loaded sentences with no filler. The final clause about text_markdown is slightly redundant given an output schema exists, but the overall shape is efficient.

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 an output schema present, the description need not explain return values, and the nested 'request' object is fully documented in the schema. The fetcher's contract (robots, rate limit, size/type bounds) is covered well enough to call it correctly.

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 url, max_bytes, accepted_types, timeout_s and job_ref. The description names max_bytes and accepted_types but adds no format, unit, or limit semantics beyond what the schema states, so the baseline 3 applies.

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'), and the phrase 'under the web-source contract' plus the accepted_types/max_bytes scope make it distinct from extraction-oriented siblings like web_extract. It stops short of naming that sibling outright, so it is clear but not fully differentiated.

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?

'Fetch one web page' implies the usage context (retrieving raw page content rather than extracting structured data), but there is no explicit when-to-use, when-not-to-use, or named alternative. Guidance is only implied.

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