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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered and the trailing "Read-only" is redundant. The description does add value beyond the annotations by explaining what compare_to computes (added/removed/changed values per element) and what "balance" means (new clashes, lost or shrunk contacts, removed elements' partners, written elements without body). It still does not describe the shape of the returned history entries or pagination behavior.

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?

The text is short and the comparison semantics are front-loaded, which is good. But it reads as telegraphic fragments ("Thorough finish: ...", "verdict partial or undetermined: untested, never clean") whose grammar makes the meaning ambiguous, so compactness is not fully paying off in clarity.

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?

There is no output schema, so the description carries the burden of explaining return values; it partially does by describing the history-with-branches, the per-element diff, the balance signal and the verdict states. Given three parameters and a comparison-heavy tool, an agent is still left guessing the concrete response structure and how branches are represented.

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 limit, cursor and compare_to are already documented in the schema and baseline is 3. The description enriches compare_to semantically by defining the per-element diff categories and the balance notion, but it says nothing about limit or cursor, adding no meaning there beyond 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 identifies the resource ("revision history with branches and where you stand") and that compare_to produces a per-element diff, but it is a noun phrase with no clear verb and never says explicitly that it returns the list of revisions. It does not differentiate itself from siblings such as restore_revision or get_model_summary, leaving the agent to infer that this is the read-side counterpart to restore.

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?

"Thorough finish: compare_to the revision you started from" gives one concrete usage pattern for compare_to, and "verdict partial or undetermined: untested, never clean" hints at interpretation of a clean/not-clean state. However, there is no guidance on when to call this versus other inspection tools or on when to omit compare_to entirely, so usage is only implied.

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