Read an official page

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

The description adds meaningful behavioral context beyond the annotations: it mentions the tool is 'live, respecting robots.txt', which is not covered by readOnlyHint or idempotentHint. It also clarifies the output behavior (passages around focus). While it doesn't discuss rate limits or error handling, the annotations already cover safety, and the added details are useful. No contradiction with annotations.

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 two sentences, with the primary action and restriction front-loaded. Every phrase serves a purpose: it states the action, the live/robots.txt behavior, the focus-passage output, and the domain restriction. No fluff or redundancy.

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 that an output schema exists, the description does not need to detail return values. It covers the tool's purpose, the key behavioral nuance (robots.txt), and the focus mechanism. The only minor gap is the lack of explicit guidance on error cases or what happens when the URL is not on an official domain, but these are not critical for an agent to call the tool 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 coverage is 67% (url and focus have descriptions, max_chars does not). The description adds value for the 'focus' parameter by explaining it is used to return surrounding passages, which complements the schema's example. However, it does not explain 'max_chars' or its constraints, and the description does not fully compensate for the missing schema description on that parameter.

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 verb 'Fetch', the resource 'official Swiss page', and the specific behavior of returning passages around a focus word. It also imposes a domain restriction, which distinguishes it from generic web-fetch tools and sibling tools like search_official_info. The purpose is unmistakable.

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 does not explicitly state when to use this tool versus alternatives, nor does it name any sibling tool. It implies usage for reading a specific official page (since it says 'typically from search_official_info' in the parameter schema, but not in the main description). The guidance is implicit, relying on the agent to infer that this is for fetching a known URL rather than searching.

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