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

Beyond the readOnly, idempotent, and openWorld hints, the description adds valuable behavioral context: the call is immediate and non-blocking, the heartbeat ID is a 256-bit bearer secret, and no authentication is required. This gives the agent important security and execution expectations not present in annotations.

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?

Four short sentences, each carrying distinct value: the action, the purpose, the non-blocking behavior, and the security characteristics. The description is front-loaded and free of filler.

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 single-parameter read tool with an output schema, the description fully covers what the tool does, when to use it, how it behaves, and what security context applies. Nothing essential for selecting or invoking the tool 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 coverage is 100%, so the parameter is well documented structurally. The description adds meaningful semantic context by calling the ID a 256-bit bearer secret and stating no authentication is required, which helps the agent understand the sensitivity and usage of the single parameter.

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 clearly states the tool reads one heartbeat immediately and enumerates what it can inspect (armed, late, fired, expired, next deadline). It is specific about the resource and action, but it does not explicitly differentiate from the sibling ping_heartbeat, so it stops short of full sibling distinction.

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?

The description provides a clear use case: inspect a heartbeat's state and next deadline without waiting. It does not mention when to prefer ping_heartbeat or when not to use this tool, so it lacks explicit exclusions and alternative routing, but the context is clear enough for correct use.

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