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

Annotations only cover the safety profile (not read-only, non-destructive, open-world); the description adds the owner check, the Brand-plan dependency, and the non-obvious failure behavior of returning an upgrade link instead of erroring. 'Saves what is given' hints at partial-update semantics, though it doesn't say whether omitted fields persist or are cleared.

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?

Two sentences, front-loaded with the action and the surface it affects, then the save behavior and access constraint. The parenthetical on the Brand plan and its $2 price is the only non-essential detail, and it earns its place by explaining the plan-gate mentioned later.

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-optional-parameter mutation with no output schema, the description covers access control, side effects, and the upgrade-path return. What is still missing is what a successful response looks like and whether a partial call overwrites or preserves existing brand settings.

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 100%, so constraints like the 40-character name, the 150 KB/PNG-JPG-WebP logo and the hex color are already documented in the schema. The description only restates the three field names, adding no new syntax or formatting meaning, so the baseline 3 applies.

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 names a specific verb+resource: it puts the user's name, logo and color on the reader-facing pre-open page for artifacts and data rooms, and clarifies the resource (reader page) rather than the artifact itself. That is enough to separate it from update_artifact/update_link without opening a schema, though it never names a sibling explicitly.

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 a real prerequisite in 'Only the space owner can change it' and explains the plan-gated path ('if the plan is not on yet, returns a link where the user turns it on'). It stops short of stating when to prefer this over general artifact/link update tools, so the usage guidance is implied rather than comparative.

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