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

Annotations cover the mutation/safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), and the description adds real behavior: it returns a ping_url, defines lateness as period plus grace, and discloses the alert chain (inbox message and optional owner email) plus the 'up to 10 jobs' cap. Return/limit context is valuable given there is no output schema.

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?

Four dense sentences, purpose front-loaded, no filler; the 'up to 10 jobs' cap closes it cleanly. Slightly run-on in the alerting sentence but every clause carries information.

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 mutation tool with no output schema, it supplies the missing return context (ping_url) and the post-creation alert lifecycle, and notes the registration limit. Combines with 100% schema coverage and annotations to make the tool callable without guessing.

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 coverage is 100%, so baseline is 3, but the description adds the causal interaction the schema one-liners lack: grace_minutes is 'extra time' added to period_minutes to define lateness, inbox_instance_id receives the alert, and email_owner triggers owner email. That clarifies how the params combine rather than just restating them.

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 concrete verb ('watch a job') and resource (backup/cron/pipeline), and 'with your heartbeat-monitor' pins down the subsystem. It implicitly separates itself from heartbeat_status/remove/update siblings by being the creation tool, though it never names them.

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?

The workflow ('make the job call it after every run') implies when to use the tool, but there is no explicit when-to-use vs heartbeat_update/status/test guidance and no stated prerequisites for registering a job. Usage is inferable but not spelled out.

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