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

Annotations already establish readOnlyHint=true and destructiveHint=false, and the description aligns with these while going further by explicitly saying the tool never signs or publishes. It also adds useful behavioral context about the heartbeat being short-lived and tied to presence-only delegation.

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 concise sentences with zero filler. The core scope sentence comes first and the important non-signing/non-publishing caveat is placed immediately after for clear front-loading.

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 two-parameter tool with full schema coverage and an output schema present, the description is complete. It provides the functional scope, the presence-delegation precondition, and the safety boundary, leaving no critical guidance 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 description coverage is 100%, so the schema already explains both parameters: agent is an EVM address and tokenId is an NFH token id. The description adds no parameter-specific meaning beyond that, which is acceptable since the schema is already clear.

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 names the action ('prepare'), the resource ('a short-lived heartbeat'), and the exact scope ('agent with an active presence-only delegation'). The qualifier 'Never signs or publishes' gives an explicit boundary that distinguishes it from the many sibling prepare_* and submission tools.

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?

It supplies a precise usage condition: only for agents with an active presence-only delegation. It does not name a specific alternative tool to choose instead, but it communicates a strong exclusion ('Never signs or publishes') which helps the agent understand when not to rely on this for publishing.

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