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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description goes beyond annotations by disclosing the refusal behavior for races with no published forecast and specifying what forecast components the result includes, which adds meaningful behavioral context.

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?

Two sentences carry all the essential information with no redundancy. The return contents are front-loaded, the input formats and refusal edge case are in the second sentence, and every clause earns its place.

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 a fully documented schema, an output schema, and annotations covering read-only and idempotent behavior, the description fills the remaining gaps: scope, accepted input formats, and the refusal case. Nothing needed to select and invoke this tool correctly is missing.

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 100%, so the baseline is 3, but the description adds genuinely useful guidance: 'Pass what the user said' instructs the agent not to normalize input, and it clarifies valid forms ('Ohio', 'OH', 'CA-12'). The office parameter is already fully documented by the schema enum and descriptions.

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 verb ('forecast') and resource ('one 2026 US election'), and enumerates what the call returns: win probability, predicted margin, poll/fundamental source, movement, and candidates. This clearly differentiates it from the sibling tools, which concern chamber-level outlook, accuracy, and member profiles.

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?

The description makes the intended use clear: a single race forecast for a state, state code, or district, with an office enum. It gives concrete input formats and notes an explicit refusal case, but it does not explicitly state when to prefer this tool over siblings such as chamber_outlook, so it stops short of a 5.

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