Send a LinkedIn Message (Partner API)

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

The description adds meaningful behavioral context beyond the annotations by warning that the tool is not available with standard OAuth apps and that it will return a clear error message explaining the limitation. This is valuable because it sets expectations that the call may fail in the current auth context. No contradiction with the annotations exists.

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 well-structured: purpose first, then an important warning, then a note about error behavior, then parameters. The Args section is somewhat redundant with the schema, but the overall layout is scannable and free of unnecessary filler.

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 three flat params and no output schema, the description covers the parameters, required auth access, limitation behavior, and output format. It does not describe the shape of a successful response, but given the explicit statement that an error message will be returned under the common standard-OAuth setup, the context is adequately complete.

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 the schema already documents all parameters. The Args block restates the same information with only minor formatting details, such as '1-2000 chars', which duplicates the schema constraints. It adds no new semantic guidance like recipient ID format examples or message encoding details.

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 begins with a specific verb and resource: 'Send a direct message to a LinkedIn member.' This clearly distinguishes it from sibling tools like linkedin_create_post or linkedin_get_feed, which operate on different resources or actions.

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 states the critical prerequisite: standard OAuth apps cannot use this tool, and Messaging API partner access is required. This tells the agent when the tool cannot be used, though it does not explicitly name alternative tools or direct the agent to alternatives when unavailable.

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