fetch_url

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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral fact — output is Markdown — but says nothing about JavaScript-rendered pages, authentication, rate limits, payload size, or failure behavior on unreachable URLs.

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 with the core action and the Markdown output front-loaded; nothing important is buried. The second sentence largely restates the first ('read the content of any web page' vs. 'fetch a single URL and convert its content'), a small redundancy that keeps it from a 5.

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, single-resource fetch tool whose annotations already cover safety and openness, the description covers what it does and what it returns (Markdown). The remaining gaps — rendering behavior and error handling — are moderate but not critical for correct invocation.

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 both the url and followRedirects parameters are already documented structurally, including the default of true for redirects. The description adds no additional semantics such as URL format constraints or the consequences of disabling redirects, 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 ('Fetch') plus the resource ('a single URL') and the transformation applied to the result ('convert its content to Markdown'), which is more information than the name alone conveys. It does not explicitly distinguish itself from siblings such as scrape_docs or read_page, which likely also retrieve page content, so an agent must infer the boundary.

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?

'Use this tool to read the content of any web page' gives a use case, but it is broadly scoped to 'any web page' with no exclusions and no mention of when a sibling like scrape_docs or read_page would be preferred. Usage is implied rather than delineated.

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