Subscribe to a feed

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

Discloses the auto-discovery and download process, plus duration, which adds value beyond the annotations (idempotentHint=false, destructiveHint=false). However, it does not clarify whether subscribing to an already-subscribed feed creates a duplicate or returns an error, leaving an important behavioral gap.

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 the primary action, and every phrase contributes essential context. No wasted words.

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?

Given the tool's modest complexity (3 params, no output schema, minimal annotations), the description adequately covers the core behaviors and side effects. Missing details like return value or error conditions, but acceptable for a straightforward subscribe operation.

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 baseline is 3. The description reinforces the schema's meaning (e.g., website-to-feed discovery, category auto-creation) but does not add new semantic information beyond what the param descriptions already provide.

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?

Clearly states the verb 'Subscribes to a feed' and distinguishes the resource. The description adds specificity by noting that the URL can be a feed or website, and contrasts with sibling tools like update_feed and unsubscribe_feed through the distinct action of subscribing.

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?

Implies usage context (add a new feed) and provides helpful notes about URL flexibility and potential delay, but does not explicitly state when to use this tool versus alternatives (e.g., update_feed for modifying existing feeds) or when not to use it.

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