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

Goes well beyond the annotations by enumerating the concrete side effects: the robot is freed, the not-yet-live control token is revoked, the host is notified, and nothing is charged. It also discloses an automatic server-side cancellation path, so an agent understands the null-action case. This matches destructiveHint=true without contradicting it.

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, zero filler. The eligibility constraint and side effects are front-loaded before the secondary auto-cancellation caveat.

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?

Covers eligibility, side effects, billing, and the automatic-cancel edge case for a single-parameter mutation, which is close to complete. The one gap is return behavior (there is no output schema, so an agent can't tell what a successful cancel returns or what errors look like for a lease already ACTIVE).

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?

Only one parameter with 100% schema coverage, so the schema already carries the documentation burden and baseline is 3. The description adds mild value by implying ownership scoping ("one of your leases") and constraining the id to a REQUESTED/CONFIRMED lease, but says nothing about format or error behavior for a wrong-state id.

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?

States a specific verb (cancel) and resource (one of your leases) plus the exact eligibility window (REQUESTED or CONFIRMED, before ACTIVE). The parenthetical state names distinguish it cleanly from activate_lease and return_lease without needing to open their schemas.

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 the condition for use (lease must still be REQUESTED or CONFIRMED) and implicitly routes post-ACTIVE cases elsewhere via "before it goes ACTIVE". The auto-cancellation note is useful guidance that sometimes no call is needed, though it never names return_lease as the explicit alternative.

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