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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description's addition of 'without fetching page content' reinforces the read-only nature without contradicting it. The phrase 'Fast and cheap' adds contextual behavior about performance. While it does not detail other behaviors like rate limits or result formatting, the annotations and output schema cover those gaps, so this is a solid score.

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 fluff. The primary action is front-loaded ('List the URLs on a website'), followed by a concise usage hint. Every word earns its place, achieving high clarity in minimal space.

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?

The tool's core purpose is clear, and an output schema exists to explain return values. However, the description omits any explanation of the 'limit' and 'search' parameters, which are non-obvious. For a tool with only three parameters, failing to document two is a notable gap that could cause misuse. The description is sufficient for basic calls but incomplete for advanced 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 0% – the description doesn't mention any parameters. It only says 'List the URLs on a website,' which implicitly covers the required 'url' parameter, but it fails to explain 'limit' (a default of 100) or 'search' (a nullable filter). With 0% coverage, the description had to compensate, but it doesn't, leaving two of three parameters opaque to the agent.

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: 'List the URLs on a website' and explicitly clarifies it does 'without fetching page content.' This clearly distinguishes it from siblings like 'crawl' and 'scrape' which fetch content. The title 'Map a site's URLs' aligns perfectly with the description, making the purpose unambiguous.

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 clear context: 'Fast and cheap. Use this to understand a site's structure before deciding what to scrape.' This tells the agent when to use the tool (as a preliminary step) and hints at the alternative (scraping). However, it does not explicitly name alternatives or state when not to use it, so it stops short of a perfect 5.

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