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

Annotations already carry the safety profile (readOnlyHint=false, destructiveHint=true, openWorldHint=false), so the description's burden is lower. It adds genuine behavioral context beyond the annotations: existing members are preserved (additive, not replacing) and where the UUID inputs originate. It does not state permission requirements or behavior on duplicate/invalid UUIDs.

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?

Front-loaded with the core action, then a short bulleted when-to-use block, then preservation and source-of-input detail. Every sentence earns its place, though the single-bullet 'Use this tool when' block is slightly heavier formatting than the content warrants.

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?

An output schema exists and annotations cover the safety profile, so return values and reversibility need not be spelled out. The description covers the mutation semantics and input provenance; only failure modes (duplicate membership, invalid/foreign UUIDs, permission errors) are unaddressed.

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, but the description goes further by telling the agent where to obtain account_user_uuids (list-account-users, list-account-team-members for copying between teams, or user-referenced UUIDs). That is real value beyond the schema's plain type definitions.

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 (add/attach) and resource (account users as team members) with clear scope: one or more users, added to a team. It also distinguishes itself from detach-account-users-from-team and from team-level update tools by clarifying that existing members are preserved.

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 an explicit trigger ('Use this tool when: The user asks to add people to a team') and names the inverse sibling (detach-account-users-from-team) for removal. It does not discuss edge cases such as users already being members or when to prefer update-account-team, so it stops short of a 5.

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