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

Annotations already mark this as a write operation with readOnlyHint=false and destructiveHint=false, so the description does not need to restate safety. It adds the auth-like constraint 'a group you are in', which is useful context. It does not disclose duplicate-member behavior, failure modes, or permission requirements beyond membership, but the annotation coverage lowers the burden.

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 a single sentence that front-loads the action, resource, parameter, and scope without filler or redundancy. It earns its place and is appropriately concise for a simple two-parameter mutation.

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 only two required parameters and an output schema, the description plus schema is mostly complete: the agent knows what to do, which parameters to provide, and the membership constraint. It lacks edge-case behavior such as handling duplicate members or nonexistent names, but those are not necessary for correct initial invocation. A little more contrast with group_invite would make it fully 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?

The schema documents 'group' as 'Group id or name' but leaves 'name' undocumented. The description adds that 'name' refers to the member's name, which is a small semantic contribution beyond the schema. It still does not clarify whether the member must already exist or what identifier format is expected, so it only partially compensates for the 50% schema coverage.

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 uses a clear action verb ('Add'), a specific resource ('a member by name'), and a scope condition ('to a group you are in'). This makes the tool's purpose immediately understandable and distinguishable from the many finance/group tools. It does not explicitly name a sibling alternative like group_invite, so it stops just short of a full 5.

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 phrase 'a group you are in' provides a clear eligibility condition, which gives some usage context. However, the description gives no explicit when-to-use or when-not-to-use guidance, and it does not contrast this tool with adjacent siblings such as group_invite. Usage context is implied rather than fully specified.

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