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

Annotations already declare readOnly, idempotent, and non-destructive behavior, so the safety profile is covered. The description adds useful substance beyond that by naming the payload (REST record plus row_count), which partially compensates for the missing output schema; it still says nothing about not-found/error 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?

Two short sentences, zero filler, with the core purpose front-loaded and the disambiguation pointer second. Every clause earns its place.

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 two-parameter read tool with no output schema, the description covers purpose, the reference-by-id model, and a partial view of the return shape. What remains thin is the meaning of contact_list_id and any error/not-found semantics, but an agent has enough to invoke it 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 50%: organization_id is documented in the schema but contact_list_id is not. The phrase 'by id' hints at the required identifier but adds no format, source, or constraint detail 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 states a precise verb (read), resource (one contact list), and scope (of the workspace, by id), which cleanly separates it from the sibling list_contact_lists. It also clarifies the record is the REST contact-list record including row_count, so an agent knows exactly which object it gets back.

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?

It explicitly routes the row-reading use case to a named alternative (list_contacts), which is genuine when-to-use guidance. It does not explicitly contrast with list_contact_lists, though 'one ... by id' implicitly implies that distinction.

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