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

Annotations declare readOnlyHint=false and destructiveHint=false, so the agent knows this is a mutating but non-destructive call. The description adds that it is a keep-alive that marks the kernel online, which is useful context. It omits idempotency, expected cadence/rate limits, and what happens on a missed heartbeat, so it adds value but not depth.

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 action and effect, then the caller and alternative. Every sentence earns its place with no 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 heartbeat tool with full schema coverage and annotations, the description covers what it does, who calls it, and how it relates to the alternative. Missing cadence semantics and failure behavior are minor for a keep-alive, and there is no output schema to explain.

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 kernelId, status, and capabilities are already documented in the schema. The description adds no parameter-level meaning (e.g. status transitions or capability format), so the baseline 3 applies.

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 (Send) and resource (per-kernel heartbeat) plus the effect (keep the kernel marked online). It distinguishes itself from the operator relay heartbeat concept, which is the relevant sibling (operator_heartbeat). It stops short of naming that sibling tool directly, but the differentiation is clear.

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?

Identifies the caller (pcc-node daemons) and positions the tool as an alternative to the operator relay heartbeat, which gives an agent a real condition for choosing it. It does not state explicit exclusions or when NOT to use it, but the contextual routing is clear.

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