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

With no annotations, the description carries the full burden of disclosing behavior, but it only states that the tool is free and requires no key or registration. It does not explain side effects, what happens when contact is made, or how marketplace-related parameters like api_key and agent_id fit in. The claim of 'no key' also creates ambiguity against the schema's api_key field.

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 brief and front-loaded, stating the relationship to contact_sphere and the target audience in the first sentence. The second sentence about being free adds some value, though it points to a possible contradiction with the schema.

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 tool with five optional parameters, no output schema, and no annotations, the description is too thin. It does not explain the query actions, the role of api_key and agent_id, the meaning of requested_action values, or what a successful contact looks like. The dependency on 'same as contact_sphere' leaves too much unresolved.

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%, so all five parameters already have descriptive text. The description adds no meaning beyond saying the tool is 'structured and typed,' which is already reflected in the schema's enum values and structured_payload description.

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 identifies this as a structured, typed variant of contact_sphere for non-linguistic clients, which distinguishes it from the sibling tool. However, it never states what contact_sphere itself does, so the actual purpose depends on an undefined reference. The verb and resource are only implied, not explicitly described.

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 clearly indicates the intended use case: non-linguistic clients such as ROS2 robots via ros2_mcp. This implies when contact_sphere might be less appropriate, though it does not explicitly mention alternative tools or draw a hard exclusion boundary.

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