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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds that subscriber counts are included in the details, which is useful context. However, it does not disclose other potential behaviors such as error handling or response structure beyond this single detail.

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?

A single, concise sentence that front-loads the primary purpose and includes the key detail (subscriber counts). No wasted words or redundancy.

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 simple read-only retrieval tool with complete parameter schemas and rich annotations, the description is mostly sufficient. It mentions subscriber counts but leaves other possible return fields unstated. Given the tool's simplicity and no output schema, a 4 is reasonable—slightly above the minimum viable.

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 description coverage is 100%, with both api_key and list_id thoroughly described. The description adds no extra parameter semantics beyond what the schema already provides, so the baseline of 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's function: getting details of a specific contact list, including subscriber counts. It distinguishes itself from sibling tools like list_contact_lists (which lists all lists) by emphasizing 'specific' and the detail content.

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 when needing details of a single list, but it does not explicitly mention when to use it over alternatives like list_contact_lists or update_list. Context signals and sibling names provide hints, but the description itself lacks explicit guidance.

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