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

Despite readOnlyHint, openWorldHint, and idempotentHint annotations already covering safety, the description goes far beyond them. It discloses that unknown metric_type/match_subtype legs are never paired, that compatibility_codes[] can be non-empty even when matches exist, that temporal_alignment null means 'could not be computed' rather than aligned, that Kalshi fees are not modeled so spreads are gross, and exactly what each compatibility code means. This is exemplary behavioral disclosure.

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 with many caveats, and nearly every sentence adds distinct value. It is well-structured with section markers like TWO MODES, RESPONSE, SAFETY FIELDS, and explicitly calls out codes and counters. It could be trimmed slightly, but the density is justified by the need to prevent misuse.

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's complexity, the absence of an output schema, and the many edge cases involved, the description covers everything an agent needs: modes, response shape, safety fields, compatibility codes, skipped-leg counters, fee caveats, and the unreliability of pre-mapped topics. No critical behavioral or interpretive gap remains.

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 100%, so the schema already documents all three parameters and their example formats. The description adds meaningful semantics beyond the schema by explaining that explicit parameters override the topic-mapped side and that both modes run the identical token-overlap matcher. This is a clear improvement over baseline, though it does repeat some schema content.

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 clearly identifies the tool as computing cross-venue spreads between Kalshi and Polymarket for the same resolving question, with the first sentence stating the core action and scope. It also explains the two operating modes (topic shortcuts and explicit ticker/slug pairing). It does not explicitly differentiate itself from sibling tools like polymarket_arbitrage, so it stops just short of a 5.

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 explicit guidance on when to use topic mode versus explicit mode: topic mode auto-fetches pre-mapped events, while explicit mode allows custom pairings. It also provides strong when-not-to-use context by warning that most pre-mapped topics return compatibility warnings and that pre-mapped does not mean tradeable. It does not name alternatives among sibling tools, so it is not a perfect 5.

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