Unosend MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the action ('Add') but doesn't clarify if this creates a new contact or updates an existing one, what permissions are required, whether the operation is idempotent, or what happens on failure (e.g., invalid email). This leaves critical behavioral traits unspecified for a mutation tool.

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 redundancy. It's front-loaded with the core action and resource, making it easy to parse. There's no wasted verbiage, and every word contributes to understanding 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?

For a mutation tool with no annotations and no output schema, the description is incomplete. It doesn't explain what happens after adding (e.g., returns a contact ID, error responses), behavioral constraints, or how it interacts with sibling tools like 'list_contacts'. Given the complexity of creating a contact with multiple fields, more context is needed for safe and effective 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 description coverage is 100%, with all parameters clearly documented in the schema itself. The description adds no additional parameter semantics beyond implying that 'audience_id' and 'email' are involved. This meets the baseline of 3 since the schema adequately covers parameter meanings, but the description doesn't enhance understanding further.

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 ('Add') and resource ('a contact to an audience'), making the purpose immediately understandable. It distinguishes itself from siblings like 'list_contacts' or 'validate_email' by focusing on creation rather than retrieval or validation. However, it doesn't specify what constitutes a 'contact' beyond the parameters, leaving some ambiguity about the resource scope.

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., audience must exist), exclusions (e.g., duplicate contacts), or related tools like 'list_audiences' for reference. The agent must infer usage from the tool name and parameters alone, which is insufficient for optimal selection.

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