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

With no annotations, the description carries the full burden and does reasonably well: it discloses that invocation is paid (0.01 USDC on Base via x402, 12 sats Cashu NUT-24, or 12 sats via L402), and that output is capped at 500 entries. It stops short of error behavior for non-sitemap URLs, gzip handling, or whether index children are followed.

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-loaded with the actual function and output shape, with no filler. The second sentence is long because it enumerates three payment rails, but that detail is materially relevant to invocation, so it earns its place.

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?

No output schema exists, so the description correctly spells out return content (count plus up to 500 entries with lastmod, changefreq, priority). What is missing are the input format specifics and failure modes for a one-parameter parser, but it is largely self-sufficient.

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?

One required parameter at 0% schema coverage, so the description should compensate, but it never explains the url format (absolute URL, .xml, gzipped, index vs child sitemap). The intent of the parameter is only implied by the tool name.

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 and resource: 'Parses an XML sitemap or sitemap index', and immediately characterizes the output (URL count, entries, lastmod/changefreq/priority). This clearly separates it from ambiguous siblings like parse_feed, robots, or links without needing to open the schema.

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?

There is no guidance on when to reach for this tool versus siblings such as robots, parse_feed, site_audit, or links, nor any prerequisite/exclusion conditions. The only decision-supporting content is pricing, which tells the agent what it costs but not when it is the right choice.

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