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

Annotations already cover read-only/idempotent/open-world, and the description adds genuinely new behavior: SSRF-safe fetching, a probe-then-parse cascade, the exact output item fields, and — critically — a per-success price of $0.005 USDC via x402 on Solana plus an alternate HTTPS endpoint. Cost and payment mechanics are absent from annotations and schema, so this is high-value disclosure.

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 core action and mechanism, then tapers into format support, output shape, safety, and pricing. It is a single dense paragraph with little waste, though the trailing endpoint URL and price sentence make it longer than strictly necessary for selection.

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?

With no output schema, the description compensates by naming the returned fields (title, link, ISO published date, author, summary, categories, enclosure). Combined with the disclosed cost model, SSRF guarantee, and supported feed formats, an agent has everything needed to decide and call 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?

Schema description coverage is 100%, so the baseline is 3. The description reinforces that a feed URL is acceptable for the url param and explains the probe fallback in prose, but it adds no syntax or edge-case detail (e.g. what happens when probing fails, or how items=0 interacts with the probe flag) beyond what the schema already says.

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 ('find a website's RSS/Atom/JSON feeds and read the latest items') and enumerates the mechanisms (link rel=alternate parsing, path probing, RSS 2.0/RDF/Atom/JSON Feed parsing). This clearly separates it from siblings like http_probe, robots_sitemap, or opengraph, which fetch pages but do not resolve 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: use it against a site URL for discovery, or pass a feed URL directly to parse it, and notes the fallback probing path. It does not say when NOT to use it or name alternatives (e.g. robots_sitemap for sitemap discovery, url_links_extract for generic link extraction), so it stops short of full routing guidance.

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