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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description adds genuine value by clarifying the blast radius: events are preserved and editing windows are not reset, and user confirmation is required before interrupting access. That softens an otherwise alarming destructiveHint. It does not cover auth needs or what the mutation returns, which keeps it from a 5.

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 purpose is front-loaded, but the body is a wall of text dominated by topics irrelevant to deactivating a feed: subscription_open_url handoffs, webcal link preservation, mailbox limitations, and ICS explanations. Every sentence does not earn its place in this tool's definition.

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 three-parameter mutation with full schema coverage and no output schema, the essentials are present (confirmation requirement, side-effect scope, revision safety implied by the schema). However, it omits what the tool returns and how the new status is reported, while spending most of its length on tangential subscription-sharing guidance.

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% and all three parameters (feed_id, expected_revision, request_id) are fully documented in the schema, so the baseline is 3. The description adds nothing about parameter usage — no mention of how to obtain feed_id or expected_revision.

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 ('Deactivate a feed') and immediately distinguishes it from adjacent behaviors ('without deleting events or resetting editing windows'). It also distinguishes it from get_feed_status and publication.status, though it never names its most obvious sibling, reactivate_feed.

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 one real usage rule ('Confirm the user wants to interrupt subscription access') and points to get_feed_status for current availability, which is useful. But these are buried in a long paragraph of unrelated mailbox/ICS guidance, and there is no explicit guidance on when to reactivate vs. simply re-fetch.

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