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

Annotations cover the safety profile (readOnlyHint=true, openWorldHint=true), and the description adds the crucial non-schema detail that each call costs $0.005 USDC via x402 or credits. That cost/paid-invocation disclosure is exactly the kind of behavior annotations cannot express, though nothing is said about rate limits or failure modes.

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?

Two sentences, front-loaded with purpose and then the cost constraint; every clause carries information with no filler.

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 parser, the definition covers purpose, output normalization, and the paid-call requirement. With no output schema, a hint about the normalized item fields would have made it fully complete, but nothing essential for invoking it is 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 100%, so both 'url' and 'limit' are already documented in the schema itself, establishing the baseline of 3. The description adds no format guidance (e.g., accepted URL schemes, limit bounds) beyond the schema.

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 (Parse) and resources (RSS, Atom, JSON Feed) plus the output shape (normalized JSON items). No sibling tool handles feeds, so an agent can select this unambiguously from extract_page, tools_sitemap, or the lookup_* tools.

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?

The description says what it does but never states when to use it or when to prefer an alternative; with no sibling handling feeds there is little routing ambiguity, but no context or prerequisites are offered either. A note on when a feed URL is appropriate versus extract_page would have earned credit.

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