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

Annotations already disclose that this is a non-read-only, non-idempotent, non-destructive write operation. The description adds useful behavioral context by saying a row with neither profile URL nor email is rejected, and that bulk input should use the upload 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 three compact sentences, front-loads the core action, states the validation rule, and routes to the bulk alternative without any wasted text.

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 14-parameter mutation with fully documented schema fields and annotations, the description covers the essential selection and invocation constraints. It does not cover duplicate handling or return behavior, but those are less central because the schema documents all parameters.

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 baseline is 3. The description adds meaningful semantics beyond the schema by stating that at least one of profile URL or email is required, which is not captured by the schema's only required field (campaignId).

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 states a specific verb and resource: adding one prospect to a campaign. It also scopes the operation to LinkedIn profile URL and/or email, and explicitly distinguishes it from the bulk sibling campaign_upload_leads.

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?

It gives clear usage guidance: use this tool for one prospect, but for more than a handful use campaign_upload_leads. It also states the minimum identifier requirement, so the agent knows when a call is invalid.

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