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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description adds substantial behavior beyond them: overwrite semantics ('previous values are not kept'), the keep-current-value rule for omitted fields, and the full side-effect chain of designating an own brand (leaves segments, sheds ignored marks, previous own brand reverts to discovered, null clears it). That is exactly the kind of destructive side-effect disclosure an agent needs.

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?

Every sentence carries information and the optional-field rule is stated plainly. The lead sentence about overwriting is placed before the identity sentence ('Update an existing project'), which slightly buries the purpose, and the own-brand passage is dense with domain jargon, but there is no filler.

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 3-parameter mutation tool with no output schema, the description covers purpose, mutation semantics, partial-update behavior, and the tricky brand_id side effects, with annotations covering safety. Only error/failure behavior (e.g. unknown project_id or brand_id) is left unstated, a minor gap.

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 adds genuine meaning beyond the schema for `brand_id`: the 'own brand' concept, its implicitness in every segment, that it is never ignored, and the null-to-clear behavior. The schema's brand_id text partially overlaps this, which keeps it from a 5, but the added conceptual framing is real value.

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 states a specific verb and resource ('Update an existing project') and enumerates the mutable fields, so it is unmistakably distinct from create-project-tool, delete-project-tool and get-project-tool. It does not explicitly name a sibling, but the resource/verb combination is 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?

It gives clear operational context: 'Every field is optional, so send only the fields to change; a field that is omitted keeps its current value,' which tells the agent exactly how to call it. It also explains when to pass `brand_id` and when to pass null. There is no explicit statement of when NOT to use this tool or which sibling to prefer, 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.