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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds valuable behavioral context beyond annotations by explaining cursor-based pagination (using next_cursor) and enumerating the exact status filter values, which helps agents understand expected iteration behavior.

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 short, purposeful sentences. It front-loads the primary purpose immediately, then efficiently covers pagination mechanics and filter options without unnecessary prose.

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 list operation with all optional parameters and no output schema, the description covers the essential invocation details: scope, pagination, and filtering. It does not describe the full response shape, but the mention of next_cursor and the simple nature of the tool make this acceptable. Minor gap: no explicit indication that limit defaults to 50, though this is in the schema.

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 descriptions cover q, limit, and cursor, but status has no schema description. The description compensates by listing all supported status values and explaining the cursor's relationship to next_cursor, adding meaning beyond the raw schema. This is particularly helpful given the 75% schema coverage.

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 states the specific verb 'Lists' and the resource 'workspace's subscribers', clearly differentiating it from sibling tools like list_campaigns and list_suppression. The pagination and filter details reinforce the scope without ambiguity.

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 by naming the action and resource, but it does not explicitly state when to use this tool versus alternatives or provide any exclusion conditions. It gives functional guidance (pagination, filtering) but not comparative usage guidance.

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