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

Beyond annotations that already declare this as a read-only, open-world, idempotent operation, the description adds concrete operational limits: 8-second timeout, 5 redirects, 768 KiB size cap, and 1,000-entry maximum. It also discloses that only uncompressed XML sitemaps are handled and that index expansion is not automatic.

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?

Four tightly packed sentences with no waste. The core behavior is front-loaded, followed by usage guidance, an important limitation, and operational constraints in a logical order.

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 two-parameter read-only fetch tool with an output schema, the description covers the essential behavioral context: output shape, non-recursive expansion, and hard limits. Nothing an agent needs in order to invoke it correctly appears to be missing.

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 50%, with the url parameter well documented in the schema and max_entries left without a description. The description adds the 1,000-entry cap, which indirectly clarifies the max_entries upper bound, but it does not explain the parameter's purpose, default behavior, or how truncation is signaled.

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 ('Fetches one uncompressed XML sitemap') and clarifies the two possible outputs: URL entries or child sitemap references. It distinguishes this tool from siblings like inspect_robots and extract_links by positioning it for sitemap-based site structure discovery.

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?

It gives a clear use case ('site structure discovery') and an explicit exclusion: sitemap indexes are not recursively expanded, so each child must be called separately. It does not explicitly name alternative tools, but the usage context is clear enough to route the agent correctly.

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