Unosend MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool lists contacts but doesn't describe what 'list' entails—e.g., whether it returns all contacts, supports pagination, includes filtering options beyond audience_id, or provides error handling for invalid IDs. For a read operation with zero annotation coverage, this leaves significant gaps in understanding the tool's 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 a single, efficient sentence that directly states the tool's purpose without unnecessary words. It is front-loaded with the core action and resource, making it easy to parse. Every part of the sentence earns its place by clearly conveying the tool's function.

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 complexity of listing contacts (a read operation with potential for large datasets) and the lack of annotations and output schema, the description is incomplete. It doesn't address behavioral aspects like pagination, error cases, or return format, which are crucial for effective use. For a tool with no structured output information, the description should provide more context to compensate.

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 input schema has 100% description coverage, with 'audience_id' documented as 'The audience ID'. The description adds no additional meaning beyond this, as it doesn't explain what an audience is, how to obtain an audience_id, or constraints on valid IDs. With high schema coverage, the baseline is 3, as the description doesn't compensate but also doesn't detract from the schema's information.

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 action ('List') and resource ('contacts in an audience'), providing a specific verb+resource combination. It distinguishes itself from siblings like 'list_audiences' or 'list_emails' by focusing on contacts within a specific audience context. However, it doesn't explicitly differentiate from 'create_contact' or other contact-related tools beyond the listing action.

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 provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., needing an existing audience), exclusions, or comparisons with sibling tools like 'list_audiences' (which might list audiences rather than contacts) or 'create_contact' (which creates rather than lists). Usage is implied but not explicitly stated.

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