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

Goes far beyond annotations: details free tier limits (2,000 URLs/12 files), paid tier pricing (5,000 URLs/20 files for $0.004 USDC), payment error behavior (x402 v2 PaymentRequired object with fields), retry mechanism, charging rules (invalid input never charged), and fetch behavior (robots.txt respect, user-agent, private address refusal). Highly informative.

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?

Front-loads purpose and discovery mechanism, then tiers, payment, and behaviors. Well-structured and dense with information, but slightly long. Every sentence adds value, though could be marginally tightened.

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?

Complete for a read-only extraction tool: covers discovery, tiers, payment flow, error handling, and fetch constraints. No output schema, but the description implies return format (URLs with lastmod). Annotations cover safety, and description adds extensive behavioral context.

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 coverage is 100%, and the description provides context about the url parameter (domain vs. sitemap file) and bulk (paid tier), but does not add syntax or format details beyond the schema. Baseline 3 is appropriate when schema does the heavy lifting.

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 (list/extract) and resource (pages from sitemaps), and details how discovery works (robots.txt, common paths, sitemap indexes). Distinguishes from siblings like robots_txt_check and url_status_check by focusing on sitemap URL extraction with lastmod.

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?

Provides clear context: use by passing a domain to discover sitemaps or a specific sitemap URL. Describes free vs. paid tiers, when paid is needed (bulk=true), and error handling. However, does not explicitly compare to sibling tools (e.g., when to use this versus seo_meta_tags_check).

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