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

Beyond readOnlyHint and openWorldHint, the description discloses key behaviors: results are sorted closest race first, prices are never estimated, unpriced seats return null, and the call requires no key. It also clarifies the price semantics (Democrat-win implied probability where provable, otherwise favorite contract in cents), which is exactly the kind of ambiguity that could otherwise cause mis-inference.

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 dense but information-carrying, leading with the map scope and moving through fields, ordering, and edge-case behavior before closing with query examples. It is slightly long, but nearly every clause adds distinct data an agent needs; there is no filler or tautology.

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 input schema and no output schema, the description carries the full burden, and it covers return fields (holder, role, rating, forecaster bands, price, URL, hub), ordering (closest race first), and null behavior. The examples and no-key note make the tool callable without further documentation.

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 tool takes zero parameters, so there is nothing for the description to map to schema fields; the baseline for no-parameter tools is appropriate. The phrases 'in one call' and 'Free, no key' usefully signal that no arguments or authentication are needed.

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 names a specific deliverable ('2026 U.S. Senate map in one call') and enumerates its contents: each seat holder, role, structure rating, forecaster bands, Kalshi price, and per-seat URL. It is distinguishable from siblings like race_odds by being explicitly the whole-map aggregate rather than a single race or generic odds scan.

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 'Use for' section lists concrete triggers such as '2026 Senate map', 'which Senate seats are toss-ups', and 'what does the market say about Senate control race by race', giving an agent clear guidance on when to call this tool. It does not name sibling tools as alternatives or state when not to use this tool, so it stops short of a full when/when-not guide.

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