comparison_build

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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), so the description's added value is the edge-case behavior: ok:true with comparison null when fewer than two runs exist. It also pins the spec version (V6, ADR-064), which is useful provenance but stops short of describing the comparison payload structure.

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?

Three compact sentences, front-loaded with what the tool does and ending on the degenerate-result case. The V6/ADR-064 parenthetical is internal jargon that consumes space without helping an agent invoke the tool.

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?

With no output schema, the description does partial duty by sketching the return content and the null-comparison case. Given only two obvious required params, that is close to sufficient, though the exact comparison object shape and the dataset_id semantics remain undocumented.

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 load. It clarifies current_run_id ('use the current run id'), which is genuinely helpful, but says nothing about dataset_id or the relationship between the two identifiers.

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: a same-dataset historical run comparison returning per-run overall/dimension scores, issue counts, and deltas. It is clear what the tool produces, but it never names or contrasts the close sibling drift_compare, so the agent must infer the boundary itself.

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 only implied by the phrase 'same-dataset historical run comparison' and the note to pass the current run id. There is no explicit when-to-use or when-not-to-use guidance versus drift_compare or trends_list, and no stated prerequisite that two prior runs must exist for a meaningful result.

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