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

Annotations already mark it read-only and idempotent, and the description adds substantial behavioral context: tier-based access (Free gets a structured tier_required response, Builder gets a window, Pro gets full history) and the note that history accrues only from when archiving started, so early results may be short. This not only complements annotations but enriches them with access-control and data-availability details.

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 somewhat lengthy but each sentence carries weight: it front-loads the core function, then explains tier restrictions and history accrual, and ends with clear use-case routing. It is structured logically and avoids fluff, though it could be tightened slightly by trimming parenthetical examples.

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?

Given the tool's tiered access and the absence of an output schema, the description covers the critical context: what data is returned (opened/current/movement), the tier_required response for Free, and the window difference between Builder and Pro. It also clarifies data availability limitations. Minor gaps like exact pagination or field names are not essential for correct invocation, and the explicit use-cases make it complete enough for an agent.

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 covers 80% of parameters (only 'limit' lacks description), so the description need not compensate. The description does not add parameter-specific meaning beyond the schema examples (e.g., 'total_bases', 'mlb'), and it stays focused on tool behavior rather than parameter syntax. It meets the baseline for high schema coverage.

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 states a specific verb and resource: 'Chronological line/odds history for a player prop' with opened/current/movement. It clearly differentiates from siblings by explicitly naming scan_movers and get_prop_evidence as alternatives for different use cases, making the tool's unique scope (timeline of ONE prop) unambiguous.

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?

Provides explicit when-to-use examples ('has this line moved since it opened', 'what did this prop open at', 'the timeline of ONE player prop') and when-not-to-use with named alternatives (scan_movers for board-wide movement, get_prop_evidence for movement delta). This gives the agent concrete routing rules.

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