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

Annotations already flag destructiveHint=true and idempotentHint=false; the description adds real context beyond them: the required calendar:write scope, the two-phase dry-run-then-confirm pattern, unknown-field rejection, and the fact that the first call mutates nothing. It stops short of saying what the destructive part actually destroys (that the previously issued subscription URL stops working, and whether that is immediate or reversible).

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?

Front-loaded with purpose and scope requirement, then the two-call mechanics in order. Every clause carries information the agent needs — the failure mode (unknown argument refused by name) and the human-approval gate are not padding.

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 one-parameter destructive mutation with no output schema, the description covers the flow, the prerequisite scope, and the shape of the intermediate response (summary + confirm_token). Gaps remain around the post-rotation state (is the old link dead, are other clients affected) and whether re-submitting with the same token is safe given idempotentHint=false.

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% and the description's statement about omit-then-supply confirm_token merely restates the schema's own parameter description. It adds a little by revealing that the token originates from the first call's response (there is no output schema), but no format or lifetime details for the token.

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?

"Replace my calendar subscription link" states a specific verb (replace) and resource (calendar subscription link), which cleanly separates it from siblings like create_calendar_feed, get_calendar_feed, and export_calendar. An agent can identify the operation without opening the schema.

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 gives explicit procedural guidance: two calls, the first is a no-op validation, and the second only happens after the person agrees. It does not, however, contrast with siblings (e.g., use create_calendar_feed when no feed exists yet) or state preconditions such as an existing feed being required.

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