history_diff_tool

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

With no annotations, the description carries the full behavioral burden. 'Diff' implies a non-destructive read, but the description never confirms read-only behavior, does not explain what a null index resolves to, and gives no operational context (history scope, project_path effect).

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 zero filler, which is structurally good. It errs toward terseness for a three-parameter tool, but no sentence is wasted.

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?

Given 0% schema coverage, no annotations, and three optional params whose null defaults change behavior, the description is far too thin. The output schema covers return format, but an agent still lacks what it needs to decide defaults and choose this tool over other history tools.

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 0% and the description adds nothing about the three parameters. 'Two history indices' loosely maps to from_index/to_index, but project_path is unexplained and the default-null semantics of the index params (which is behaviorally critical for a diff) are completely undocumented.

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?

Uses a specific verb ('diff') on a specific resource ('two history indices') and states the outcome ('showing what changed between them'), which separates it from history_undo/redo. However, it never differentiates itself from the other history siblings (history_list, history_status_tool, history_goto_tool), and 'history index' is left undefined.

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?

No when-to-use guidance, no prerequisites, and no mention of alternatives such as history_list or history_goto_tool. It also doesn't say what to do when an index is omitted, which matters because both index params are nullable with null defaults.

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