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

Annotations already declare readOnly, idempotent and non-destructive, so the safety bar is covered. The description adds genuinely useful behavior beyond that: a 30-minute refresh cadence, the 20-game season-plus-last-season window, the last-change/home-coach assumption, and the exact edge formula. Auth or coverage caveats are not mentioned.

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?

Front-loaded with the deliverable and efficient overall, but the opening sentence is heavily nested with parenthetical metric lists, which slows parsing slightly. The with/without-team clauses are well structured and earn their place.

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 carries the full burden and does so: it enumerates the returned stats, explains the edge computation, documents the two response shapes by team parameter, and notes refresh cadence. An agent has everything needed to call and interpret it.

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 goes further by defining the semantics of min_edge (edge = expected 5v5 xG share against the matchup minus 50) and explaining how the team parameter changes the entire response payload, which the schema alone does not convey.

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 resource (tonight's NHL forward lines and D pairs) with precise metrics (5v5 per-60 rates, expected time share, matchup edge defined as xG share minus 50). It is clearly distinguishable in content from invoke_nhl_team_matchups or invoke_nhl_lines, though it never names a sibling explicitly.

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?

It gives clear, actionable context for the two invocation modes: no team returns lines with edges plus a compact per-game card, while supplying a team returns every line/pair plus PP, PK and 5v5 rates. It stops short of stating when to prefer this over alternatives like invoke_nhl_lines or invoke_nhl_team_matchups.

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