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

Annotations already declare this is a non-read, non-idempotent, non-destructive write. The description adds genuinely new behavioral context beyond that: the server assigns the timestamp and client-supplied time is rejected, which tells the agent what it cannot control. It stops short of explaining the idempotentHint=false consequence (repeated calls recording separate heartbeats).

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 tight sentences, zero filler. The core action and its liveness effect are front-loaded, with the timestamp constraint as a supporting clause.

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 one-parameter write with an output schema and full annotation coverage, the description supplies the essentials: ownership scope, liveness semantics, and server-side timestamp authority. Only idempotency behavior and any rate-limit expectations are left unstated, which is a minor gap.

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% and the single slug parameter is fully documented in the schema, including its source (public profile or list_agents). The description adds only the ownership constraint, so the schema does the heavy lifting and 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 and resource ('Record a push-style heartbeat for an agent you own') and clarifies the effect ('marking it alive right now'). This functionally separates it from read-oriented siblings like get_agent_health or check_agent_trust, though no sibling is named explicitly.

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 phrase 'for an agent you own' implies an ownership prerequisite, which is useful context. However, there is no explicit guidance on when to call this versus get_agent_health or how frequently heartbeats should be sent, leaving usage to inference.

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