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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered externally. The description usefully adds the status enum values (waiting, up, late, down, paused) and clarifies what owner_email means, but says nothing about permissions, pagination, or incident 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?

A single front-loaded sentence listing the returned fields with no filler. It is slightly dense as a field dump, but every element earns its place given there is no output schema.

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?

With no output schema, the description does the work of explaining the returned fields and status values, which is appropriate for a 2-parameter read tool. Only the lack of alternatives/routing guidance keeps it from being fully complete.

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 instance_id and passport_token are fully documented in the schema itself; the description adds nothing about either parameter, including which is required. Baseline 3 applies when the schema carries the parameter burden.

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?

Names the resource (heartbeat checks) and enumerates the exact fields shown, so an agent knows this is a read/list tool for heartbeat state. It does not explicitly distinguish itself from siblings like heartbeat_add/remove/update, but the read-only framing plus the title make the intent unambiguous.

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?

There is no when-to-use or when-not-to-use guidance, and no sibling is named as an alternative (heartbeat_add, heartbeat_update, heartbeat_remove all exist). The read-only nature of the operation is only implied by the field listing.

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