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

Annotations already indicate a non-read-only, non-destructive, idempotent operation, and the description adds meaningful behavior beyond that: the PROFILE_ALREADY_LINKED failure mode, the restriction that API-key callers may only link private leads, and that global leads are read-only for user-supplied data. No contradiction with annotations.

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?

Three dense sentences, front-loaded with the action and purpose, followed by input requirement, failure behavior, and permission constraints. Every sentence earns its place and there is no 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 moderate-complexity mutation with six parameters and no output schema, the description covers intent, input requirements, failure mode, and authorization boundaries. It could additionally describe the successful result/return value, but the core information needed to select and invoke the tool correctly is present.

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 coverage is 100%, so the baseline is 3. The description adds a valuable constraint not expressed in the JSON schema: at least one of url, externalId, or handle is required, even though only leadId and platform are marked required. This materially helps an agent avoid an invalid call.

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 action ('Attach a platform profile') with a clear resource and scope ('existing PRIVATE lead'), and explains the outcome ('sequenceable across channels'). It is immediately distinguishable from the sibling unlink_lead_profile and other lead-related tools.

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?

Provides clear context: when to use (to link LinkedIn/X profiles to a private lead), a required input condition ('Provide at least one of url, externalId, or handle'), and caller restrictions. It does not explicitly name the alternative unlink_lead_profile or state 'use this instead of X', so it stops short of full when-to-use versus alternatives guidance.

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