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

Adds substantial context beyond annotations: billing ('Free within feed allowances'), no automatic monitoring enrollment, retry semantics for request_id, and the critical caveat that publication.status is file preparation, not subscription access. Slightly diluted by lengthy URL-handoff presentation rules that concern sharing UI rather than this tool's own execution, and it never states the response shape for the created object.

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?

Purpose and prerequisites are correctly front-loaded, but roughly half the text is a policy block on sharing links (subscription_open_url, subscription_options_url, manage_url, filtered_subscription) that is only tangentially about creating a feed. Several sentences are UI-script instructions rather than tool semantics, which blunts the signal.

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?

No output schema exists, and the description does name the fields an agent will encounter (publication.status, distribution_ready, returned URLs) and warns not to treat unpublished feeds as subscribable. It stops short of describing the actual response payload or failure modes, so it is strong but not fully self-contained for a mutation tool.

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?

With only 40% schema description coverage the description must compensate, and it does so for request_id (opaque, reuse on retries) and implicitly for events ('extract the schedule yourself'). However, 'activate', 'title', and 'description' parameters get no clarification, and the required 'events' array structure is only touched via the extraction instruction rather than explained.

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?

Opens with a specific verb+resource ('Create and activate a subscription calendar from structured events') and adds a key prerequisite ('Extract the schedule yourself first'). It distinguishes itself from reading siblings by pointing to get_feed_status for current availability, though it does not contrast with apply_feed_changes or reactivate_feed, which are the closest alternatives.

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?

Gives explicit negative guidance for unsupported actions ('explain the limitation without reading feeds or substituting an edit') and tells the agent to gather events itself rather than assume monitoring. Clear context, but no explicit statement of when to prefer apply_feed_changes or reactivate_feed over creating a new feed.

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