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

Goes well beyond the readOnly/idempotent annotations by disclosing the paywall lifecycle: free forecast first, then a degraded 'free part' with no chances for unplayed lines, and a `deskPass` whose `message` must be relayed to the person. It also names the two error conditions (free_forecast_used, desk_pass_required), which is exactly the kind of auth/rate context annotations cannot express.

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-loads what the tool does and what it returns before the calling guidance and the paywall mechanics. It is dense and slightly clunky in the middle ('the Desk's estimate of how they play now'), and the final sentence packs two error codes plus a gating rule, but nothing is truly wasted.

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 six parameters, no output schema, and a paywall, the description covers what is returned qualitatively, how the free/paid split behaves, and the error surface. What is missing is the shape of results when no opponent is supplied versus when one is, leaving the agent to infer the return structure.

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 every parameter is already documented, including the 'never fill it in yourself' rule for `lineup` and the averaging effect of `unavailable`. The description restates those constraints rather than adding new meaning, so the baseline 3 applies.

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 ('Plans a doubles and singles lineup for a team the Desk covers') and enumerates what comes back: appearances, usual line, Desk level, per-line win chance, expected lines won. It never names the closest sibling (plan_lineup_from_availability), but the distinction is implied by the rule that `lineup` is only what the person states, so an agent can mostly tell them apart.

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?

Gives three literal trigger phrasings ('what lineup should we play against X', 'who has played most for us', 'how do we beat X') plus the gating rule that it needs a Desk Pass after the member's free forecast. No explicit when-not-to-use statement or named alternative, which keeps it below a 5.

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