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

This is a strong behavioral disclosure. It explains that the matcher works by keyword/token overlap, that `compatibility_warning` can be non-empty even when pairs are returned, that fees are not modeled, that spread values are gross rather than net tradeable edge, that unknown-type legs are never paired, and that `temporal_alignment` null means 'could not be computed,' not aligned. All of this goes well beyond the read-only/idempotent annotations and contradicts nothing.

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 long, but the tool is genuinely complex and the length is mostly earned by covering modes, response fields, safety codes, and caveats. The core action is front-loaded in the first sentence, and the two-mode structure is clearly labeled. It loses a point for some redundancy and a wall-of-text presentation; tighter sectioning would improve skimmability without losing information.

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 carries full responsibility for explaining the response, and it does so thoroughly: leg-by-leg prices, `top_spreads_pp`, compatibility codes, per-entry flags, skipped-leg counters, fees note, and temporal alignment semantics. It also gives real-world calibration by warning that pre-mapped topics are not automatically tradeable. Nothing an agent needs to invoke the tool and interpret its results 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?

Although the input schema already describes all three parameters (100% coverage), the description adds meaning beyond the schema: it clarifies that `topic` is a pre-mapped macro shortcut, that the explicit parameters override the topic-mapped side, and that both modes run the identical token-overlap matcher. It also lists the exact valid topics and gives examples, so an agent can confidently select and combine parameters.

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 opens with a specific statement of what the tool computes: 'Cross-venue spread between Kalshi and Polymarket for the same resolving question.' It also names the two operational modes (`topic` and explicit ticker/slug pairing), which makes the tool's scope concrete and distinguishes it from single-venue or pure-arbitrage siblings, even though no explicit sibling alternative is named.

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 gives clear when-to-use context: you can use pre-mapped topic shortcuts or explicit `kalshi_event_ticker` + `polymarket_event_slug` pairings, and it explains what happens in each mode. It also cautions that 'most pre-mapped topics return compatibility_warning today; pre-mapped ≠ tradeable.' However, it does not explicitly contrast this tool with nearby siblings like `polymarket_arbitrage` or `polymarket_edges`, so the decision boundary against alternatives is implied rather than fully explicit.

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