add_subscriber

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

No annotations provided; description adds that tool returns created subscriber and mentions compliance requirement, but lacks details on errors, rate limits, or side effects beyond schema.

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 with no redundant information. First sentence states purpose, second adds return value and compliance context. Efficient and front-loaded.

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 3-parameter creation tool with no output schema, the description covers essential aspects: action, compliance, return value. Lacks detail on nested 'properties' object but sufficient for basic use.

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%, and description repeats schema descriptions without adding new insight beyond rephrasing. Baseline score 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?

Description clearly states action (add), resource (phone number to SMS list), and specific mechanism (using keyword ID). Emphasizes TCPA/CTIA compliance, distinguishing it from sibling tools like list_subscribers or get_keyword_id.

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?

Provides context that keyword_id ties to consent flow, implying need for prior existence, but does not explicitly state when to use or alternatives. Lacks explicit when-not guidance.

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