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

The description enriches the annotations (readOnlyHint, idempotentHint) with non-obvious details: default page size (30), sorting (newest first), fields included (id, name, url, type, status, check frequency, uptime), and notably that an empty list is returned instead of an error when no monitors match. This goes well beyond what annotations convey.

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?

The description is three sentences long, each adding unique value: core function, entry field details, and usage guidance plus edge behavior. It's front-loaded with the primary purpose and wastes no words.

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 read-only list tool with well-annotated parameters and a provided output schema, the description covers all necessary aspects: pagination, sorting, filtering capabilities, entry fields, and error behavior. It leaves no significant gaps for an agent to understand how to use the tool effectively.

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?

The input schema already documents all three parameters with clear descriptions and enums, giving 100% coverage. The description adds value by stating the default page size ('30 per page') and the empty-list behavior for no matches, which are not in the schema. However, these are minor additions relative to the schema's completeness.

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 states the tool's purpose: 'List the monitors on the account, newest first, 30 per page.' It further distinguishes itself by noting the returned 'id needed by every other tool' and provides a concrete use case for the status filter. This makes it highly specific and separates it from sibling tools like get_monitor.

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 description explicitly states when to use this tool: 'Start here when the request names a monitor by name rather than by id, and when asked what is broken - filtering by status "down" answers that in one call.' It provides clear contextual guidance, even though it doesn't mention alternatives by name. The 'start here' and specific use case give strong usage direction.

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