add_group_membership

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

Annotations only note this is not read-only, idempotent, or destructive; the description adds substantial behavior: never guess dates, temporal_basis inference rules, defaults for role and sensitivity, and that concurrent and historical memberships are kept. This goes well beyond the annotations, though it does not mention confidence handling or ID validation behavior.

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 purpose is front-loaded, and every sentence adds operational value—date-unknown handling, temporal_basis semantics, defaults, and retention behavior. The description is dense but not padded, and the detail is warranted given the complex date semantics.

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 write operation with tricky temporal semantics, the description is largely complete: it covers what to record, how to handle missing dates, how temporal_basis works, and defaults. The main gaps are the absence of confidence-field guidance and any explicit statement about what happens when IDs do not correspond to existing people or groups, though 'existing' is asserted in the purpose.

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?

With schema description coverage at 0%, the description compensates meaningfully: it defines temporal_basis values and inference, explains valid_from/valid_to handling, and states role and sensitivity defaults. It does not explain confidence or explicitly walk through every property, but the most semantically complex parameters are well covered.

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 opening sentence, 'Record that an existing person held a role in an existing group,' states the exact verb and resource. It clearly distinguishes this membership-recording action from sibling tools like create_group, close_group_membership, or set_relationship.

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 description gives clear context for when to use the tool: recording stated/confirmed memberships with role and date semantics. It does not explicitly name alternative tools or state exclusions, but the purpose and constraints are unambiguous enough to route an agent correctly.

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