fetch_url

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

With no annotations provided, the description carries full burden for behavioral disclosure. It reveals the Readability extraction behavior, default markdown output, and the impact of options like includeLinks and maxChars. This goes beyond minimal disclosure, though it omits potential error behaviors or rate limits, which are not essential for this simple tool.

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 no redundancy. The first sentence states the core function and default behavior, while the second lists options and use cases. It is front-loaded with the key action and every clause contributes value.

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 simple four-parameter tool with a fully described schema and no output schema, the description covers the operation, options, and ideal use cases. It does not address error handling or rate limits, but these are not critical for this tool's primary functions. The description is sufficiently complete to guide usage.

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 baseline is 3. The description mentions format options, includeLinks, and maxChars, but essentially restates what the schema already provides. It adds no new semantic meaning beyond the schema descriptions, so a 3 is appropriate.

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 explicitly states 'Fetch a URL and return its main readable content as clean markdown by default (Readability extraction)', giving a specific verb ('fetch') and resource ('URL'), and clearly distinguishes from sibling tools by focusing on readable content extraction. This differentiates it from extract_links (link extraction), fetch_image (image fetching), and search_content (content search).

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 explicit use cases: 'reading a web page, understanding a code/docs page, or getting article content without boilerplate.' It does not explicitly mention alternatives or when-not-to-use, but the context is clear enough to guide selection. The inclusion of sibling tool names in context also helps, but no direct comparison is made.

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