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

Goes well beyond the annotations: it explains that the lease is reset to now + ttl, that a missed lease returns the task to READY, that later writes raise lease_lost, and that note/progress survive into the auto continuation pack. These failure-mode and data-retention details are exactly the context annotations cannot convey (readOnlyHint=false, destructiveHint=false only say it is a non-destructive write).

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, each earning its place: the action first, then cadence, then consequences. Nothing is redundant and the critical instruction is front-loaded.

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?

An output schema exists, so return values need no explanation, and the description covers cadence and failure semantics for a state-mutating lease tool. The only real gap is the undocumented agent parameter and any behavior on an invalid or expired lease_id.

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 0%, so the description must carry parameter meaning, and it only partly does: it clarifies the lease being extended and that note and progress are persisted into the continuation pack, but the agent parameter is never mentioned and no format or range guidance is given. Useful but incomplete compensation for a documentation gap.

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 action and resource: 'Keep a lease alive: extends it to now + ttl.' An agent immediately knows this is a lease-extension operation, distinguishable from release_lease or list_leases. It never names those siblings explicitly, but the verb+resource pair is unambiguous.

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?

Gives a concrete usage rule ('Send every heartbeat_interval_s') plus the consequence of not doing so, which tells the agent exactly when to call it. It stops short of naming alternatives or exclusions, notably the confusingly similar sibling presence_heartbeat, so it does not reach a 5.

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