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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds two traits not in structured data: a concrete cost of 10 credits and the data-coverage boundary (meetings back to 1999 only). It stops short of noting result limits or pagination, which keeps it from a 5.

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?

A single dense sentence, front-loaded with the use case and followed by output details and cost. The clause 'where our games start' is slightly cryptic phrasing for the data-coverage cutoff but carries real information.

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?

An output schema exists, so return values need no explanation, yet the description still summarizes them usefully. Combined with the credit cost and historical cutoff, an agent has enough to call it correctly; only edge behavior such as what happens with an unknown team code is unaddressed.

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?

With 100% schema description coverage, the schema already documents team codes, the limit cap, and the season/omit-for-all-time behavior. The description largely restates the season semantics ('over one season or every meeting since 1999') and adds little about the team1/team2 code format or how limit interacts with the two modes.

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?

States a specific verb and resource ('compare two teams' history') and enumerates exactly what comes back: recent meetings with scores, the win/loss record, and average margin. No sibling tool covers head-to-head comparison, so the agent can route here without ambiguity.

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?

'Use to compare two teams' history' gives an implied trigger but no explicit when-not or named alternative (e.g., get_game_detail for a single meeting, get_team_stats for aggregate form). The season-vs-all-time scope hint partially guides parameter choice but is framed as capability, not usage guidance.

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