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

Annotations declare readOnlyHint=false / destructiveHint=false, so the safety profile is covered; the description adds the precondition that the task must be held by the caller's worker. It omits failure behavior (lease already expired, worker mismatch), and the 4-hour/30-second lease bounds are only in the schema.

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 short sentences, front-loaded with the purpose, with the API link relegated to the end. The documentation URL is arguably padding rather than substance, but nothing is buried.

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 no-output-schema mutation tool with 67% schema coverage, the definition is minimally adequate but misses default lease duration, the maximum extension window, and the failure mode when the lease has already expired. It gives enough to attempt the call but not enough to call it well.

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 67%, and the description adds no parameter meaning at all. lease_seconds has no description in the schema beyond its min/max bounds, so the most operationally important parameter (how long the extension lasts, and what the default is) is undocumented in both places.

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?

The description gives a specific verb+resource ('Extend the lease on a task') and scopes it to tasks 'currently held by one of the caller's workers,' which separates it from claim_task or complete_task. It stops short of naming a sibling alternative, but an agent can tell what this tool does at a glance.

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?

There is no when-to-use guidance: nothing about renewing before lease expiry, what happens if the lease already lapsed, or why one would renew rather than re-claim. The precondition ('currently held') is implied by the purpose statement but never framed as usage criteria.

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