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

Annotations already declare idempotency and non-destructiveness, but the description goes further: it discloses a quota cost ('Spends one monitor'), the exact return payload (ping URL plus crontab, GitHub Actions, Kubernetes CronJob, systemd snippets), and the precise idempotency semantics (same plan id returns the first result and the same URL). That is context an agent cannot get from the annotations alone.

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 precondition, then payload, then cost, then idempotency, then the exclusion. No sentence is redundant and each carries a distinct decision-relevant fact.

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, yet the description summarizes the return value set precisely, and it covers cost, safety, and alternatives. Nothing needed to invoke this correctly is missing.

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 both parameters are already documented, and the schema's 'show it to the user first' note covers the confirm gate. The description still adds real meaning to plan_id by explaining the repeat-call behavior, though it says nothing extra about confirm beyond what the schema states.

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 specific verb+resource ('Add the planned cron job monitor') and ties it to a confirmed plan_cron_monitor plan, which uniquely distinguishes it from plan_cron_monitor and update_monitor in the sibling list.

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?

Explicit precondition ('when the user has confirmed a plan_cron_monitor plan') and an explicit exclusion naming the alternative ('Not for changing an existing job's schedule: use update_monitor'). The routing decision is fully determined.

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