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

Annotations declare it is a non-destructive, idempotent mutation; the description adds substantial behavioral detail beyond that: per-key outcome reporting (added/exists/rejected), rejection reasons (plan, active-check limit, plugin), and default trigger behavior (weekly/daily schedule plus re-runs on site changes). This is rich, non-obvious context.

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?

Two sentences, front-loaded with the action and the key source, followed by outcome and scheduling behavior. No filler; every clause carries useful 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?

With no output schema, the description fills the gap by explaining per-key results and rejection reasons, and it covers default scheduling and dependencies. For a two-parameter mutation tool this is complete enough to invoke correctly.

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 meaning by specifying that keys come from list_checks and are check keys, guiding correct value sourcing. It does not restate limits like maxItems, but that is already in 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 ('Add checks to a site') and identifies the key source ('from list_checks'), which distinguishes it from siblings like list_checks and update_check. An agent can tell what this does without opening the 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?

Directs the agent to list_checks for valid keys, giving clear context for how to use it, and notes dependencies (WordPress plugin). It does not explicitly state when to prefer an alternative tool or when not to use it, so it falls short of full routing guidance.

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