fetch_url

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

With no annotations, the description carries the full burden, and it does disclose two real behavioral facts: only public HTTP/HTTPS pages are supported, and the return is extracted 'useful text' rather than raw HTML. It says nothing about truncation behavior, fetch failures/timeouts, rate limits, or what happens on non-text content, which are significant gaps for a network tool with zero annotation coverage.

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 short sentences, zero waste, with the capability stated first and the routing guidance second. Nothing is padded or restated from the title.

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?

For a two-parameter read tool with no output schema and no annotations, the description covers purpose and sequencing but leaves the return shape and the truncation control unexplained. An agent knows when to call it but not what it will get back or how to bound the response size.

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 0%, so the description must compensate, but it only implicitly covers 'url' via the word 'webpage'. The 'max_chars' parameter — which controls truncation with a default of 12000 and a 30000 cap — is never mentioned, so an agent gets no signal that output length is tunable.

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 states a specific verb and resource ('Read useful text from a public HTTP or HTTPS webpage') and explicitly scopes it against the sibling tool ('Use after web_search when more detail from a specific result is needed'). An agent can distinguish fetch_url from web_search without opening either 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?

It gives a clear usage context and names the alternative: call this after web_search when a specific result needs more detail. What's missing is any exclusion — nothing says when not to use it (e.g., login-gated pages, JS-rendered content, or non-HTML resources), which the 'public' qualifier only hints at.

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