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

Annotations already declare non-read-only, non-destructive, non-idempotent, closed-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the change is effective-dated and prior days retain the previous team, which is non-obvious. It omits what happens when valid_from is null (default null in schema implies 'today'), whether an existing assignment on the same date is overwritten, and any permission requirements.

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?

A single sentence with no waste, front-loading the verb and resource before the temporal caveat. It is dense but readable; the semicolon clause earns its place by conveying the history-preservation rule.

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 so return values need no explanation, and the four parameters are at least named. For a mutation tool that writes dated history, the description should clarify null valid_from and overwrite behavior on re-assignment; those gaps keep it at minimum-viable-plus.

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 0%, so the description must carry the load. It does name all four concepts — email, team, cost center, and the date with its YYYY-MM-DD format — but leaves default/null behavior of valid_from and the meaning of an empty cost_center (default "") undefined.

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 ('Puts a person (email) in a team and cost center from a day'), and the temporal qualifier distinguishes it from the plain-membership siblings. It does not explicitly contrast with set_team_manager, but the assignment semantics are unambiguous.

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?

Usage is only implied: the reader can infer this is for setting team/cost-center membership effective from a date. There is no explicit when-to-use guidance, no mention of set_team_manager, change_member, or teams_and_people as alternatives, and no prerequisites stated.

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