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

With no annotations provided, the description carries the full burden. It discloses that this is a mutation ('Record') and adds a key behavioral trait: 'The server sets the timestamp; no client-supplied time is accepted.' It also states an ownership requirement. This provides meaningful context beyond the schema, though it could mention error cases or idempotency, which are not essential for a simple heartbeat.

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 two sentences with zero waste, front-loading the core purpose and then adding the timestamp constraint. Every word contributes, making it efficient and easy to parse.

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 action with an output schema (so return values are documented elsewhere), the description covers the essential behavior: what it does, ownership, and server-side timestamping. It could mention prerequisites like authentication or error handling, but those are likely implied by the platform. Overall, it is complete for an agent to invoke correctly.

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?

The schema already documents the single parameter 'slug' with a clear description ('The agent's URL slug from its public profile or a list_agents result'). Schema description coverage is 100%, so the description adds no additional parameter-specific information. The baseline of 3 applies since the schema does the heavy lifting.

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 verb 'Record' and the resource 'a push-style heartbeat for an agent you own', specifying the action and scope. It distinguishes itself from the read-only siblings (get_agent, get_agent_health, list_agents) by indicating a write operation, so an agent can tell it apart without opening schemas.

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 implies usage by saying 'for an agent you own', which gives a prerequisite condition. However, it does not explicitly mention when not to use this tool or name alternatives like get_agent_health for checking status. The context is clear but lacks explicit exclusions or routing.

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