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

Beyond the sparse annotations, the description discloses concrete behavioral traits: the service is free, input is capped at 1 MiB, output is capped at 100 items, and it neither fetches URLs nor retains feed content. This meaningfully informs the agent about limits, privacy, and external interaction. It adds substantial value over the boolean hints.

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 convey purpose, accepted formats, service limits, and behavioral constraints with zero filler. The core action is front-loaded, and every clause adds useful information.

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 simple two-parameter tool with no output schema, the description is nearly complete: it states the input format, output format ('stable JSON'), limits, and side-effect behavior. It does not detail the JSON output structure or error handling, but those are not required to invoke 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?

Schema description coverage is 0%, so the description must compensate. It does by specifying that the input is an RSS 2.0 or Atom XML feed, and that returned items are capped at 100, which maps to the 'limit' parameter. It does not explicitly mention the 'limit' name or its default of 50, but the parameter names are self-explanatory and the description adds format-level meaning.

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 uses a specific verb and resource ('Normalize one RSS 2.0 or Atom XML feed to stable JSON'.) It clearly identifies the input format, the action, and the output. The name and siblings do not blur the purpose; this is distinct from all listed sibling 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 implies when to use the tool: when you have RSS 2.0 or Atom XML and want stable JSON. It also gives useful 'not-for' context ('Does not fetch URLs'), which tells the agent this tool is not for retrieving feeds. However, it does not explicitly name alternatives or provide when-not-to-use guidance beyond that.

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