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

The description goes far beyond the read-only/idempotent annotations by disclosing the matching method ('matched by keyword and word overlap, not a shared resolution source'), the gross-vs-net fee limitation ('does not model Kalshi's fee schedule'), and the fact that compatibility_warning/compatibility_codes can be non-empty even when matched_pairs > 0. It also explains null semantics for temporal_alignment and enumerates all compatibility codes and their meaning. There is no contradiction with the annotations.

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 well-organized with labeled sections (TWO MODES, RESPONSE, SAFETY FIELDS, Codes) and nearly every sentence carries a distinct behavioral, output, or caveat fact. Some repetition—such as re-explaining null alignment semantics and repeated 'in EITHER mode' phrasing—could be tightened, so it earns a 4 rather than a 5.

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 fully carries the burden of explaining return shape and edge behavior. It documents leg-by-leg prices, top_spreads_pp sign convention (Kalshi − Polymarket), compatibility codes, per-entry flags, skipped/low-confidence buckets, temporal_alignment semantics, fees_note, and cross-type/subtype counters. An agent can safely and correctly invoke this tool with just the description.

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 schema description coverage is 100%, the description adds substantial meaning: it lists the exact pre-mapped topic values, explains that explicit ticker/slug override the topic-mapped side, and gives concrete examples like 'KXFED-26OCT' and 'fed-decision-in-june-825'. It also clarifies that both parameter modes run the identical token-overlap matcher, which is critical for interpreting results correctly.

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 'Cross-venue spread between Kalshi and Polymarket for the same resolving question', which names the specific resource and the two venues compared. It clearly explains that the tool reports raw probability deltas and flags when bet shapes are not equivalent. It does not explicitly name or contrast sibling tools, but the Kalshi–Polymarket focus and 'same resolving question' scope make the purpose unambiguous.

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 mode-level guidance: use `topic` for 10 pre-mapped shortcuts and explicit ticker/slug for custom pairings, with both running the same matcher. It also warns that most pre-mapped topics currently return compatibility_warning and ends with 'pre-mapped ≠ tradeable', which is useful when/expectation guidance. It does not name alternative sibling tools or say explicitly when not to use this tool, so it falls 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.