compare_summaries

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

No annotations are present, so the description carries the safety burden. It exposes the useful behavioral detail that FOPT/FGPT/FWPT/FPR are used by default unless keys are supplied. It does not explicitly state that the operation is read-only, but 'compare' strongly implies it and the output schema covers return shape.

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 description is a single tight sentence with no filler. It front-loads the core action and then gives the exact default behavior, making it easy to parse quickly.

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?

The output schema likely explains return values, and the description covers the main input intent. Still, an agent has to infer case identifiers and valid key formats, and the description does not point to list_cases or list_summary_vectors for resolving those values, leaving moderate gaps for a 3-parameter tool.

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 compensate. It adds meaning to 'keys' by giving the default list and indicating they may be supplied. It does not clarify how case_a/case_b should be specified or whether keys can be a comma-separated string versus an array, though the names are self-explanatory.

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 uses a specific verb ('Compare') and a specific resource ('two cases on field totals') and provides the default keys. It is clear enough to distinguish from single-case summary tools, though it does not explicitly name sibling alternatives such as field_summary or compare_to_observed.

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: use this tool when you need to compare two cases on field totals or supplied summary keys. However, there is no explicit guidance about when to prefer this over related tools, nor any stated prerequisites or exclusions.

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