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

Annotations already mark the tool as read-only and idempotent, but the description goes far beyond that: it discloses compatibility codes, non-equivalent bet shapes, unclassified leg handling, fee-schedule limitations, and skipped comparison counters. It even explains that returned pairs carry flags that should be read even when matched_pairs > 0. No contradiction with 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 densely informative and well-organized with labeled sections (TWO MODES, RESPONSE, SAFETY FIELDS, Codes). It earns most of its length given the tool's complexity and the absence of an output schema. Some minor redundancy exists around temporal alignment, where the null meaning is explained twice.

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 must carry the full burden of explaining return values, and it does: it covers top_spreads_pp, compatibility fields, skipped_unclassified, low_confidence_pairs, temporal_alignment, fees_note, and skipped counters. It also provides practical context about when pre-mapped topics return warnings, which is essential for correct interpretation.

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 baseline is 3; the description adds genuine value by explaining the semantics of `topic` as pre-mapped shortcuts and by clarifying that explicit ticker/slug override the mapped side. It also states that both modes run the same matching logic, which is not inferable from the schema alone.

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 opening sentence states a specific operation: measuring the cross-venue spread between Kalshi and Polymarket for the same resolving question. This clearly distinguishes it from sibling tools like polymarket_arbitrage, which targets arbitrage, and polymarket_edges, which focuses on single-venue edges. The two modes are named and scoped precisely.

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 usage context: it introduces the `topic` shortcut mode, the explicit ticker/slug mode, and clarifies that explicit parameters override the topic-mapped side. It also warns when not to treat output as tradeable, but it does not explicitly name when to use a sibling tool instead, so it falls short of a full 5.

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