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

Annotations already declare readOnlyHint=true and destructiveHint=false, so it is clear this is a safe, non-mutating, closed-world operation. The description adds the useful behavioral detail that comparison defaults to the current timeline, but says nothing about the shape of the diff result, which matters for a tool with no output schema.

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 front-loaded sentence with no filler; every clause carries meaning about what is compared against what. The parenthetical is slightly awkward but not wasteful, and nothing needs to be cut.

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 three-parameter read-only tool this covers the essentials of what is compared and against what. The main gap is the return shape: with no output schema, an agent does not know whether it receives a structured change list, a text diff, or counts, which affects how it would present or chain results.

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 only 33% (versionId and againstVersionId have no schema descriptions), so the description must compensate. It does meaningfully: 'a saved version' clarifies versionId's role, and 'another version' plus the default of the current timeline clarifies againstVersionId's optionality and effect. Only projectId's default is left to the schema.

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 operation on a specific resource: a diff of a saved version against the current timeline or another version. That is enough to separate it from siblings like list_versions, save_version, and restore_version, which are listed but never named. It stops short of a 5 because it doesn't explicitly distinguish itself from those adjacent version tools.

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 implied by the phrase 'between a saved version and the current timeline (or another version)', which tells an agent the intended comparison scenarios. There is no explicit when-to-use versus when-not guidance and no pointer to list_versions for discovering a versionId, nor any exclusion against restore_version for reverting.

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