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

With no annotations provided, the description carries the full burden. It adds useful behavioral traits: uses the 'newest governed fact,' requires matching units and reference periods for comparability, and explicitly returns missing/mismatched evidence. It does not disclose output format or access requirements, but for a comparison tool these are less critical.

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 two sentences, front-loaded with the primary purpose, followed by the key behavioral constraint. Every word earns its place, with no repetition of schema details or annotations.

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 the tool has no output schema and no annotations, the description covers the core aspects: what it does, the condition for comparability, and how missing/mismatched evidence is returned. It lacks a description of the successful return format, but this is partially mitigated by the tool's clear purpose.

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?

The input schema already provides 100% coverage with meaningful descriptions for all three parameters (entities, bundle, metrics). The description adds minimal parameter-level meaning beyond reinforcing the idea of 'standard economic metric' and 'resolved municipalities,' both already implied by the schema, so the baseline of 3 applies.

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 states a specific action: 'Compare 2–10 exact Saskatchewan municipalities using the newest governed fact for each standard economic metric.' This clearly identifies the verb (compare), resource (municipalities), and scope (Saskatchewan, 2–10), distinguishing it from sibling tools like compare_outcomes or compare_roles.

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?

It provides clear context for when to use the tool, namely comparing multiple Saskatchewan municipalities on economic metrics. It also specifies the comparability condition (same unit and reference period) and explicitly notes how missing/mismatched evidence is handled, but it does not mention alternatives or when not to use the tool.

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