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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false and a closed world, so the safety profile is covered. The description still contributes genuine behaviour beyond that: it operates only on non-deleted heartbeats, resumes are no-ops when already resumed ('succeeds without toggling its state'), and it will not re-enable a disabled heartbeat. It does not say what is returned or whether permissions beyond org membership are needed, which keeps it below 5.

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, no filler, and the core action is front-loaded before the edge-case caveats. Each sentence earns its place by adding a distinct constraint.

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, non-destructive, idempotent mutation with full schema coverage and no output schema, the description covers the action, the scope, idempotent behaviour and the key exclusions. Nothing an agent needs in order to decide to call it and to call it correctly 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?

There is a single required parameter and schema description coverage is 100%; the schema already explains that heartbeatExternalId is the external GUID returned as Id by HeartbeatList. The description adds nothing about the identifier format, source, or error behaviour for unknown IDs. With the schema doing all the work, 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?

The description states a specific verb and resource ('Clear a non-deleted heartbeat's paused flag') plus the scope ('in the authenticated organization'), which is far more than a restatement of the name. It also draws a boundary against a neighbouring concept ('Does not enable a disabled heartbeat'), though it never names the sibling heartbeat_pause or heartbeat_delete by name, so the differentiation is implicit rather than explicit.

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?

Usage context is clear: call this to un-pause an existing, non-deleted heartbeat. A when-not condition is supplied ('Does not enable a disabled heartbeat'), which prevents a plausible mis-invocation. It stops short of naming the alternative tool (heartbeat_pause) or describing prerequisites such as required permissions, so it falls short of a full 5.

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