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

Annotations already establish readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds a real behavioral prerequisite (history must be enabled on the table) and describes the comparison semantics (earlier time vs now, or two times). It doesn't cover what happens if history is off (error? empty result?), which would be valuable.

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?

One tight sentence with the capability, the example use case, and the prerequisite front-loaded. No wasted words.

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?

Adequate for a 4-param read-only tool with no output schema: it covers purpose, timing semantics, and the history requirement. It leaves gaps on error behavior when history is off and on result shape (e.g., per-field diffs), which for a comparison tool an agent might want to know.

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 50%; 'table' and 'record_id' have no schema descriptions, but the description implies their meaning (a record in a table). 'from' and 'to' semantics — the default-now behavior for 'to' and the 'two times' mode — are clarified in the prose, which is genuine added value 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?

States a specific verb (differ/compare) and resource (a record's fields over time), plus a concrete example question ('what changed on job 42 since Monday?'). Easily distinguished from siblings like record_history (raw history) and open_record (current state).

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?

Gives implied usage through the example question and an explicit prerequisite ('history must be switched on'). However, it doesn't name record_history as the alternative for viewing the raw change log, nor clarify when to prefer compare_record over record_history.

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