MCP URL Fetcher

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions fetching and converting to plain text, but lacks details on error handling, rate limits, authentication needs, or what happens with non-text content (e.g., images, binary files). For a tool with no annotations, this leaves significant gaps in understanding its behavior and constraints.

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 a single, efficient sentence that front-loads the key information: fetching content and converting to plain text. There is no wasted verbiage, and it directly communicates the tool's core functionality without unnecessary details.

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 the tool's complexity (fetching from URLs, which can involve network issues, varied content types) and the absence of annotations and output schema, the description is incomplete. It doesn't address potential errors, output format details (e.g., how plain text is extracted), or behavioral traits like timeouts or size limits. This leaves the agent with insufficient context for reliable use.

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?

The input schema has 100% description coverage, with the 'url' parameter clearly documented. The description adds no additional semantic information beyond what the schema provides (e.g., it doesn't specify URL formats, protocols supported, or content types). With high schema coverage, the baseline score of 3 is appropriate, as the description doesn't compensate but also doesn't detract.

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 action ('fetch content') and resource ('from any URL'), and specifies the output format ('plain text'). It distinguishes from siblings by mentioning the conversion to plain text, which suggests differentiation from fetch-html, fetch-json, and fetch-markdown. However, it doesn't explicitly name the siblings or detail how it differs from the generic 'fetch' tool, keeping it from a perfect score.

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 provides no guidance on when to use this tool versus its siblings (fetch, fetch-html, fetch-json, fetch-markdown). It implies usage for converting content to plain text, but doesn't specify scenarios, exclusions, or alternatives. This lack of explicit context leaves the agent to infer usage, which is insufficient for effective tool selection.

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