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

Beyond annotations, the description adds valuable behavioral context: it states that the status is point-in-time, that MCP does not infer availability from failures, and that affiliate fields are removed from the upstream response. These details help the agent interpret results correctly and set expectations about response sanitization.

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 a single well-structured paragraph that front-loads the core purpose, then explains status values and behavioral nuances. It is slightly lengthy due to the status definitions, but each sentence serves a purpose and there is no redundancy or fluff.

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?

Given the output schema exists, the description does not need to document return format. It explains all domain status meanings, the limits, and key behavioral quirks. It does not mention potential errors or rate limits, but for a batch read-only tool with one parameter, it is largely complete.

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 schema already fully describes the 'domains' parameter (comma-separated, max 50). The description repeats the 50-domain limit but does not add new parameter-level information, such as formatting or validation details. Hence, the description adds minimal semantic value beyond the schema, so baseline 3 is appropriate.

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 returns point-in-time availability status for up to 50 domains, with a specific verb ('Return') and resource ('Availability service'). It also defines each possible status value, distinguishing this batch tool from singular alternatives like 'available'.

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 implies usage for batch queries by specifying 'up to 50 domains' and explaining the status semantics. It does not explicitly name alternatives or exclusion criteria, but the batch scope and threshold provide clear context for when this tool is appropriate.

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