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

Annotations already indicate read-only, open-world, idempotent, and non-destructive behavior, so the bar is lower. The description goes well beyond that by disclosing that compatibility_warning/compatibility_codes can be non-empty even when pairs exist, that unknown metric_type/match_subtype legs are never paired, and that skipped counters reveal how many comparisons were dropped. It also warns that pre-mapped does not mean tradeable, providing critical behavioral 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 highly structured, front-loading purpose and modes before diving into response fields, safety fields, codes, and reliability caveats. It is dense but every section carries important operational warnings; the only minor inefficiency is repeating the topic list that already exists in the schema.

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 explains the response structure, including leg-by-leg prices, top_spreads_pp, compatibility codes, temporal_alignment, and skipped counters. It covers edge cases, warns about unverified pairings, and tells the agent exactly what to look for—making the tool callable correctly without needing additional 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?

Schema coverage is 100%, so the baseline is 3, but the description adds meaningful nuance: it explains how the two explicit parameters override the topic-mapped side and clarifies that topic is a shortcut that auto-fetches matching events on both venues. This helps the agent understand parameter interplay beyond the schema's individual descriptions.

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 plainly states the tool computes a cross-venue spread between Kalshi and Polymarket for the same resolving question, which is a specific function with a clear resource. It differentiates itself from sibling tools like polymarket_arbitrage by focusing on cross-venue comparisons, and it details the two operating modes, leaving no ambiguity about what the tool does.

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 explains when to use each mode—topic shortcuts for pre-mapped macros and explicit tickers/slugs for custom pairings—and cautions that most pre-mapped topics are not tradeable and may return compatibility warnings. It does not explicitly name sibling tools as alternatives or give 'when not to use' conditions, but the context is strong enough for an agent to decide correctly.

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