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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the description's job is to add beyond that — and it does, disclosing the hard cap of 10, newest-created ordering, non-deleted scoping, organization-level containment, and the caveat that LastCheckedAt reflects stored scheduled execution time rather than an actual check. The remaining gap is that it never says what a caller should do when more than 10 matches exist (truncation handling).

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?

Three sentences, front-loaded with the core behavior and scope, then the disambiguation, then the field-semantics caveat. No filler, and each sentence carries information an agent would otherwise have to guess.

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 still conveys the return set coarse-grained (up to 10 non-deleted monitors, newest first) and flags the one field whose name is genuinely misleading. It stops short of describing the monitor record's fields or what happens on truncation, which a schema-less list tool would ideally cover.

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 the schema already documents search, status, and includePaused in detail; baseline 3 applies. The description adds only marginal framing — that filters are applied before the top-10 selection and that state is 'effective' rather than raw — without adding syntax, precedence rules, or examples beyond the schema.

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 and resource with full scoping: 'List up to 10 non-deleted monitors most recently created in the authenticated organization, newest-created first.' It also pre-empts the most likely misreading by declaring 'This is not a list of recently checked monitors,' which separates it from monitor_latest_checks without the agent opening either schema.

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?

Provides an explicit exclusion plus the alternative to use instead ('use MonitorLatestChecks for actual checks'), which is the key routing decision for a tool whose name suggests recency of checks. It does not state when to prefer this over the sibling monitor_list (i.e., the general list endpoint), leaving one comparison to inference.

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