seal_heartbeat

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

Beyond the annotations (idempotentHint=true), the description explains why it is safe to repeat, what the return value is, and the conditions under which it fails ('Only the fence holder may extend... refused'). It also reveals the underlying purpose of preventing reclamation mid-flight, which adds meaningful behavioral context.

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?

The description is three sentences and front-loads the core behavior, then adds lifecycle guidance, return shape, failure conditions, and idempotency. Every sentence earns its place without redundancy.

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?

Given the absence of an output schema, the description correctly documents the return value ({lease_until}), the ownership requirement, the failure cases, and repeatability. For a lease-extension tool with clear annotations, nothing important is missing.

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 the schema already documents both parameters thoroughly. The description reinforces their role in the lease-extending flow but does not add substantial new parameter-level meaning beyond what is already present.

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 states a specific verb ('Extend the lease') and a clear resource (a lease for an intent), and explicitly situates it between seal_admit and seal_commit. This distinguishes it from the sibling tools by lifecycle phase and purpose.

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 clearly says when to call it ('periodically well inside the lease between seal_admit and seal_commit') and when it is refused (after lease expiry or intent close). It does not explicitly name alternative tools for when the effect is finished, but the lifecycle placement gives strong contextual guidance.

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