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

Annotations already declare idempotentHint=true, destructiveHint=false and readOnlyHint=false, and the description reinforces idempotency while adding substantive behavioral context not present in structured fields: the same-project invariant and the non-obvious side effect that attaching an ignored brand clears its ignored mark. It still omits error behavior on cross-project input and any description of the response, which is where it loses a point.

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 layered with constraints and state-transition semantics in four short sentences with no filler. The idempotency sentence partially repeats the idempotentHint annotation, a minor redundancy rather than a flaw.

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 two-parameter mutation with full schema coverage and rich annotations, this covers the invariants and the meaningful side effect an agent needs. Missing only the failure mode for mismatched projects and what the call returns, neither of which is fatal given there is no output schema to explain.

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 both parameters are already documented, including the same-project constraint on segment_id. The description's 'own brand is implicit' remark adds a little semantic color about brand_id, but the baseline 3 is appropriate since the schema carries the weight.

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+resource pair ('Attach a brand to a segment') that is immediately distinguishable from its nearest sibling detach-brand-from-segment-tool and from attach-tag-to-prompt-tool. An agent knows exactly what operation this performs without opening the schema.

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 real context on the conditions and consequences of attachment (discovered brands start being tracked, ignored brands are revived, the own brand is a no-op), which steers usage decisions. It never names an alternative tool or states an explicit when-not case, however, so it falls short of full routing guidance.

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