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

The description goes far beyond the readOnly/idempotent annotations by revealing compatibility_codes, pairing_unverified status in both modes, fee treatment, null semantics for temporal_alignment, and the fact that unclassified legs are never paired. This is rich, candid behavioral disclosure about a complex matcher.

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 front-loaded with the core purpose and organized with clear section labels like TWO MODES, RESPONSE, and SAFETY FIELDS. It is long, but the density is largely justified by the number of safety caveats; a little redundancy around temporal_alignment semantics keeps it from 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 return-value burden: it covers leg-by-leg prices, top_spreads_pp flags, compatibility fields, skipped counters, low-confidence pairs, fees disclosure, and alignment semantics. An agent has enough information to call the tool and interpret its results safely.

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 at 100% coverage, so the baseline is 3; the description adds meaningful relational meaning by explaining that explicit ticker/slug overrides replace the topic-mapped side and that both modes run the identical matcher. That is useful context beyond the field descriptions, though per-param syntax is still left mostly to the schema.

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 leads with a specific resource and task: computing the cross-venue spread between Kalshi and Polymarket for the same resolving question, and explains when the delta is a real signal. It also clearly distinguishes itself from single-venue tools by emphasizing cross-venue comparison and the same-outcome matching requirement.

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 clearly lays out two invocation modes, which parameters apply to each, and warns that pre-mapped topics are not automatically tradeable because most return compatibility warnings. It does not explicitly name alternative sibling tools or give an explicit when-not-to-use list, so it falls just 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.