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

Annotations only say readOnlyHint=false and destructiveHint=false, so the description carries the real behavioral payload: a lease is taken and an existing stale lease held by another worker is released when the task is assigned to your worker. That side effect on other workers is genuinely beyond the annotations. It stops short of the obvious follow-up cases (what happens when the task is not assigned to your worker, or when a live lease is held) and doesn't mention renew_lease for keeping 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?

Three short sentences, front-loaded with the action and then the disambiguation rule; no filler or restatement of the title. The trailing API reference URL is the one element that doesn't help an agent decide or invoke, keeping it just below maximum.

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 3-parameter tool with full schema coverage and no output schema, the description supplies the missing pieces: exclusive-lease semantics, the stale-lease release side effect, and the alternative tool. It is slightly thin on failure modes (already actively leased, task not assigned to your worker) but nothing essential for correct invocation is absent.

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%, so task_id, worker_id and lease_seconds are already documented with defaults, format and bounds. The description only reiterates 'by id' and adds no syntax, defaulting or edge-case meaning beyond the schema — the baseline 3 for fully covered schemas.

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 and resource ('Take a lease on a specific task by id') and immediately distinguishes itself from the sibling pull_next_task by the selection criterion (task_id already known). An agent can tell it apart from search_tasks, get_task, accept_task and pull_next_task without opening any 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?

Explicit routing rule: 'Use this instead of pull_next_task when you already know the task_id', plus a concrete scenario ('one that was handed off to you'). This is the exact when-to-use / alternative pairing the dimension asks for.

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