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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds useful behavioral context: it returns normalized items with specific fields (title, link, published, summary) and supports keyword filtering. It does not disclose pagination behavior, error cases, or what happens with an invalid feed id, but given the strong annotation coverage, a 3 is appropriate.

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 with zero waste. The core action and resource are front-loaded, the return format is stated compactly, and the optional filter is mentioned last. Every sentence earns its place.

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 read-only, idempotent tool with a fully documented schema, the description is nearly complete. It explains the return format and the source of the feed id. The only minor gap is that it doesn't mention pagination or the default limit behavior, but the schema already documents the limit parameter with its default. No output schema exists, so the description's mention of the return fields is valuable and sufficient.

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 schema already documents all three parameters. The description adds the meaning of the return format and the keyword filter behavior, but it does not add syntax or format details beyond what the schema provides. Baseline 3 is correct when the schema does the heavy lifting.

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 states a specific verb ('Read'), a specific resource ('curated travel feed'), and identifies the source of the id ('from list_feeds'). It also names the sibling tool it is not (list_feeds) and distinguishes itself from fetch_feed by describing the normalized output format. An agent can tell exactly what this tool does.

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 clearly states the context: reading a curated feed by id, with optional keyword filtering. It references list_feeds as the source of valid ids, which is a clear usage prerequisite. It does not explicitly state when to use this tool versus fetch_feed or other siblings, but the normalized-item description and feed-id requirement imply the distinction. No explicit exclusions or alternatives are named, so it falls just short of a 5.

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