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

Annotations already declare destructiveHint=true, so the safety posture is partly covered, and the description adds that the call creates a membership. It does not disclose idempotency (what happens if the contact is already in the group), required permissions, or whether the change is reversible — meaningful gaps for a state-mutating 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?

Three tight clauses with zero waste; the core action is front-loaded, followed by the identification rule, then the internal API mapping. Every element earns its place.

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 simple three-parameter tool with full schema coverage and no output schema, the description plus annotations give the agent enough to invoke it correctly. The remaining gap is post-call behavior on duplicate membership and error conditions, which is not addressed anywhere.

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 baseline is 3, and the description adds real value beyond the schema by establishing a preference order between group_id and group_name and forbidding their joint use. It also clarifies that contact_id covers either a contact or a company, matching and reinforcing the schema rather than merely repeating it.

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?

States a specific verb and resource ("Add a contact or company to a group") and parenthetically defines the underlying operation as creating a group membership, which disambiguates it from siblings like lacrm_get_contact_groups and lacrm_list_contacts_in_group. It does not, however, explicitly name a sibling or contrast itself with one, so sibling differentiation is inferred rather than stated.

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?

Gives a clear invocation rule: identify the group by group_id (preferred) or group_name, and explicitly excludes passing both. This is genuine when/how guidance, but it is scoped to group identification and says nothing about when this tool is the right choice versus listing or removing memberships.

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