session_heartbeat

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

The description adds real behavioural context beyond the annotations: a tier gate (pioneer_plus) and the 24h extension window. It does not say whether expiry is recomputed from now or added to the existing expiry, which is exactly the ambiguity that matters given idempotentHint=true; no mention of token/auth requirements or rate limits.

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 two-sentence core is tight and earns its place. It is front-loaded with a bracketed metadata block (capability, tier, API path, authority path) of which only the tier gate is actionable for an agent; the URL and authority fields are noise that pushes the actual purpose back.

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?

No output schema exists, so the description should say what a heartbeat returns (new expiry? remaining TTL?) and what the failure modes are. With three undocumented required parameters and nothing about the returned state, an agent cannot call this confidently beyond a blind attempt.

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 0% across three required parameters (sessionId, agentAddress, sessionToken), and the description says nothing about any of them or how the token relates to the session ID. The description is doing no work to compensate for the schema gap.

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?

"Keep an agent session alive. Extends expiry by 24h." states a specific verb and resource, plus the concrete effect of the call. It does not name how it differs from siblings such as create_session or session_key_status, so a 4 rather than 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?

Usage is implied by "keep an agent session alive" — call it while a session is active but nearing expiry. There is no explicit when-to-call, how often to call, or which sibling to use for what (create_session, grant_session_key, session_key_status all sit nearby).

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