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

Beyond the readOnly/idempotent annotations, it discloses important edge-case behavior: when a book moves the line itself, prob_shift is null and direction is 'line_moved', and those outcomes are excluded from steam. It also explains the steam[] definition, the 27-book scope, and the free-tier redaction.

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 stays tight; each sentence adds a distinct fact: output fields, steam signal definition, null behavior, uniqueness, and access tier. There is no filler.

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 does a solid job of defining the meaningful output semantics and null/edge cases. It does not describe the outer response shape or pagination, and access specifics are only hinted by 'Hobby+ full; free tier redacted,' but the schema covers the main input filters.

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 description contributes no input-parameter semantics; it focuses on output shape. Schema coverage is only 60%, and the two required parameters (sport_key, event_id) are left without schema descriptions, so the description does not compensate for that gap.

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 artifact: line movement and steam detection from snapshot tick history, and enumerates exact per-(book, market, outcome) fields: opening line, latest line, signed implied-probability shift, point shift, direction. It also differentiates from ordinary odds retrieval with 'No pull-only odds API can produce this,' so an agent can distinguish it from get_odds and get_odds_history siblings.

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 implies the use case: call this when you need line-movement and steam/wise-money signals rather than plain odds. It adds an exclusion context ('No pull-only odds API can produce this') and access-tier conditions, but it does not explicitly name sibling alternatives or spell out when-not-to-use versus each adjacent tool.

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