heartbeat

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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, so the safety and repeat-call profile is covered structurally. The description adds the 'stay visible' intent but says nothing about permissions, rate limits, or whether heartbeats expire/go stale, so with the lower bar set by annotations a 3 is appropriate.

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, front-loaded with purpose before timing and field list; nothing is wasted. The trailing field enumeration is mildly redundant with the schema, keeping it from a 5.

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 simple, idempotent write with full annotation coverage and no output schema, the description supplies purpose, call timing and payload hints — enough to invoke correctly. Missing only edge behavior such as expiry or failure handling.

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 all six parameters are already documented with types, enum-like values and clearing semantics. The description restates only current_task_id, message and metadata without adding format or default detail beyond the schema, 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 and resource ('Send heartbeat') plus its effect ('to stay visible'), so an agent immediately understands the operation. No sibling tool does presence/heartbeat, so differentiation is implicit rather than explicitly stated, which keeps it just below a 5.

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?

Gives concrete timing guidance with the required parameter value: 'Call at session START with status=online, periodically during work with status=busy.' This is clear operational context, though it never states when NOT to call it or names any alternative (e.g. session_report, update_agent_profile), so it stops short of a 5.

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