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

Annotations already signal readOnly, idempotent, non-destructive behavior, and the description goes well beyond that by disclosing the token-overlap matching approach, the meaning of compatibility codes, the gross-vs-net fee limitation, and the fact that unclassified or unknown legs are never paired. It also explains null behavior for temporal_alignment, adding genuinely useful safety context.

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 densely informative, with the core purpose in the first sentence and clear labeled sections for modes, response fields, safety fields, codes, and fee disclaimers. A few concepts are restated for emphasis, but the structure helps an agent parse the complexity without losing important caveats.

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 has no output schema, the description compensates thoroughly by enumerating key response components: leg prices, top_spreads_pp, compatibility_warning, compatibility_codes, temporal_alignment, fees_note, and skipped counters. It also explains edge cases like unclassified legs, unknown temporal alignment, and non-equivalent bet shapes, making the tool safe and usable without external 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 input schema already has 100% description coverage for all three parameters and includes examples, so the baseline is 3. The description adds meaning beyond the schema by explaining that both modes run the identical token-overlap matcher, that explicit tickers override topic mappings, and that pre-mapped topics are not guaranteed to be tradeable—this nuance helps an agent choose and combine parameters 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 clearly identifies the tool's function: computing a cross-venue spread between Kalshi and Polymarket for the same resolving question. It specifies two operational modes—pre-mapped topic shortcuts and explicit event pairings—and distinguishes the tool from nearby siblings by naming the two venues and the spread concept.

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 provides clear context for when to use the tool: whenever a Kalshi-Polymarket spread on an equivalent question is needed, and explains both input modes plus the caveat that most pre-mapped topics may not currently yield tradeable pairs. It does not explicitly contrast against alternatives like polymarket_arbitrage or polymarket_edges, 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.