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

Adds substantial behavior beyond the annotations: 50-item and 2 MB caps, lenient real-world parsing, 422 on non-feed pages with no charge, and the $0.002 x402 payment on success. The payment/charging detail also explains why readOnlyHint=false and idempotentHint=false, so the description and annotations are consistent rather than contradictory.

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 dense sentences with no filler: purpose and return fields first, then limits, then error/payment behavior. The cost disclosure is placed last where it belongs and every clause carries information an agent needs.

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?

There is no output schema, and the description compensates by enumerating the returned feed-level and item-level fields. Combined with limits, error semantics, and pricing, an agent has everything needed to call it and interpret the result.

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%, so both parameters (url, limit) are already fully documented with types, ranges, and default. The description only restates the 50-item ceiling and the shape of returned items, adding no syntax or format detail beyond the schema; baseline 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 specific verb and resource ('Read a public RSS 2.0, RSS 1.0 or Atom feed') and enumerates exactly what is returned (feed title, link, description plus item title/link/date/summary/author/id). This cleanly separates it from siblings like sitemap, url_meta, html_to-text, or extract, which fetch pages rather than parsed feeds.

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?

Gives clear context for use ('follow news, blogs, release notes or podcasts without scraping pages'), which tells the agent when this beats a generic page fetch. It stops short of naming specific alternative tools or exclusions (e.g., when to prefer sitemap or url_meta), so it is strong but not fully routing.

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