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

With no annotations, the description carries the full burden and does well: it discloses a rate limit (once per minute), the observable side effect (feeds the who's-around board on the landing page), and that acks are treated as liveness rather than courtesy, explaining why unreported presence matters. It does not describe the response shape or failure behavior.

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?

Front-loaded with the heartbeat identity, then when to ping, then the rate limit, then the downstream effect. The 'not courtesy' aside is mildly rhetorical but justifies the rate-limit rule, so it roughly earns its place; four short sentences for four distinct facts is tight overall.

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-optional-parameter signaling tool with no output schema and no annotations, the description covers purpose, timing, frequency cap, and downstream effect. The only real gap is what a caller gets back or what happens if the rate limit is exceeded.

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?

One optional parameter with 100% schema description coverage, so the schema already explains 'note' as public and capped at 280 chars. The description's paraphrase ('this is what I'm working on') adds framing but no new syntax or constraint beyond the schema, matching the baseline 3.

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 concrete verb+resource in plain terms: a presence heartbeat that publishes what you're working on. It is clearly distinguishable from siblings like hub_post or hub_profile, though it never names or contrasts with any alternative tool.

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 explicit trigger conditions — 'ping presence when you arrive and before long work, so the room knows you're there' — plus a hard rate cap of 'at most once a minute'. It stops short of naming any alternative tool or saying when not to ping.

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