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

This is a model of transparency. It discloses fee modeling limitations ('does not model Kalshi's fee schedule'), explains compatibility_codes semantics, details skipped classification behaviors, and clarifies the meaning of null temporal_alignment. It augments the readOnly/openWorld/idempotent annotations with critical caveats about gross vs net spreads and the fallibility of matching.

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-structured with explicit section headers (TWO MODES, RESPONSE, SAFETY FIELDS). It front-loads the core purpose and then systematically details safety and edge cases. While verbose, every sentence contributes necessary context for safe and correct invocation of this complex tool. The length is justified by the complexity.

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?

For a tool with no output schema but high complexity, the description is remarkably complete. It covers response structure (leg-by-leg prices, top_spreads_pp), safety fields (compatibility_warning, compatibility_codes), all possible codes, skip counts (skipped_cross_type/subtype), fee disclosure, and temporal alignment handling. An agent has everything needed to interpret results correctly without additional lookup.

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 schema already documents all three parameters (100% coverage), so baseline is 3. The description adds semantic value: it explains that kalshi_event_ticker and polymarket_event_slug override the topic-mapped side, and provides concrete examples ('fed' → 'KXFED-26OCT', 'fed-decision-in-june-825'). This goes beyond schema descriptions to clarify the interaction between 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 precise definition: 'Cross-venue spread between Kalshi and Polymarket for the same resolving question.' It clearly distinguishes itself from siblings like polymarket_arbitrage by specifying the cross-venue nature and the two modes (topic shortcuts and explicit tickers). The verb is specific ('spread'), and the resource is 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 explains both modes explicitly and when each is appropriate: use topic for pre-mapped macros, use explicit tickers for custom pairings. It also warns that 'pre-mapped ≠ tradeable' and that most topics return compatibility_warning, guiding the agent to scope expectations. It does not explicitly name alternatives among siblings, but the operational guidance is clear and actionable.

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