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

readOnlyHint already tells the agent this is a safe read, and the description adds value beyond that: it discloses the source of truth ("as stored at the current canvas head") and the authorization requirement (project:view or the project's API key). It stops short of noting payload size or any truncation behavior for large token sets, but the important preconditions are stated.

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 verb and resource, with the authorization note placed last where it belongs. The parenthetical "(colors etc.)" is slightly loose filler in an otherwise dense and purposeful description.

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 single-parameter read tool with an output schema, the description supplies everything an agent needs: what is returned, where it is read from, which tools mutate it, and what permissions are required. Return-value structure is correctly left to the output schema.

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 parameter, and it does: project_uuid is identified as the project identifier and tied to the returned data. The only remaining ambiguity is that local UUID versions are not specified, but the schema's format:uuid covers shape, so meaning is adequately conveyed.

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 ("Read a project's design tokens by project UUID") and enumerates exactly what is returned: theme, typography, sizing. It also distinguishes the tool from the mutating siblings by naming update_theme / update_typography / update_sizing as the writers of these same documents.

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 makes clear this is the read path and that the update_* tools are the write path for the same documents, which gives an agent a usable read-vs-write routing rule. It does not explicitly say when to prefer get_project or get_selection instead, so the sibling differentiation against those tools is left implicit.

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