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

Beyond the readOnly/destructive hints, the description discloses credit debits, the free first credit, credits_burned/credits_remaining in success bodies, and a detailed error contract including 401/402 handling and retry semantics. This is substantial behavioral transparency with no contradiction; the billing side effect is clearly disclosed.

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?

The definition is front-loaded with the core action, but the rest is a dense run-on paragraph mixing installation, authentication, credits, and error handling. Some details, like the golden URL, repeat the schema, and the lack of structure makes the important operational rules harder to scan.

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 paid API with no output schema, it thoroughly covers auth, cost, and failure modes. However, it never clearly specifies what the success body contains beyond credits_burned and credits_remaining, leaving the actual digest/feed response structure implicit.

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?

The input schema already fully documents the url parameter, including the public http(s) RSS/Atom constraint and the golden proof URL. The description mostly restates this and adds endpoint context, so the baseline score 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?

The description opens with a concrete action and resource: 'Fetch a public RSS or Atom feed (POST /digest).' The title reinforces the resource, and no sibling tool performs feed digestion, so an agent can distinguish it immediately without opening the schema.

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 practical invocation guidance: preferred auth scheme, the sole install path, a golden test URL, and a prerequisite workflow with quote_credits. It does not explicitly compare against alternative feed tools, but no sibling is a real alternative; the quote-first instruction is the relevant routing guidance.

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