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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so safety is covered. The description adds real value beyond them: it discloses the rate limit ('Free, rate-limited'), the return payload (feed_xml and feed_url), and the notable capability of generating feeds for sites that never had one.

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 short, front-loaded sentences with no filler; the resource and capability come first, return values and constraints follow. Efficient, though the staccato phrasing leaves little room for nuance.

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 one-parameter read tool with no output schema, the description supplies the missing return-value information (feed_xml, feed_url) and the rate-limit caveat. An agent has what it needs to call and interpret the tool correctly.

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?

Only one parameter, and schema description coverage is 100% (the schema already gives the 'Site URL, e.g. https://example.com' example). 'Pass the site url' adds no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 concrete verb+resource ('Build a feed for a site') and adds a distinguishing capability note ('including one that never published a feed'). Sibling tools are all in unrelated domains (email, logo, trends), so no sibling differentiation is needed; the purpose is 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?

'Pass the site url' implies the single required input but gives no when-to-use context, prerequisites, or when-not guidance. Adequate but lacking explicit routing or exclusion criteria.

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