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

Annotations already declare read-only, idempotent, non-destructive behavior, so the description's burden is to add operational context — and it does extensively: compatibility codes, skipped legs, temporal-alignment null semantics, fee disclosure, and gross-vs-net spreads. This directly supports the annotations without contradicting them.

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 it is front-loaded with the core purpose and organized into labeled sections (TWO MODES, RESPONSE, SAFETY FIELDS, fees, skipped counters). Every sentence carries genuine operational content; the only deduction is that the density of codes, flags, and caveats makes it a heavy read despite the clear structure.

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?

There is no output schema, so the description must explain return semantics itself, and it does thoroughly: leg-by-leg prices, top_spreads_pp with flags, skipped_unclassified, low_confidence_pairs, temporal_alignment, and fees_note. It even clarifies edge semantics like null meaning 'could not be computed' rather than aligned. Nothing needed to invoke the tool correctly is missing.

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 coverage is 100%, so the baseline is 3, but the description adds substantial semantic weight: topic is a pre-mapped shortcut that auto-fetches matching events, explicit params override the mapped side, and both modes run the identical token-overlap matcher. It also explains the meaning of the topic values and the override behavior beyond what the schema states.

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 names a specific resource — the cross-venue spread between Kalshi and Polymarket for the same resolving question — and explains what the tool does with it: matches equivalent bet shapes and reports the price delta. It clearly differentiates from same-venue siblings like polymarket_arbitrage by emphasizing cross-venue comparison and same-question matching.

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 explicitly frames TWO MODES and tells when to use pre-mapped topics versus explicit kalshi_event_ticker/polymarket_event_slug pairings. It also sets expectations with the warning that most pre-mapped topics currently return compatibility_warning and that 'pre-mapped ≠ tradeable.' It stops short of a 5 because it never names a sibling tool as the alternative for other cases.

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