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

Goes well beyond the annotations by disclosing client-dependent rendering (MCP Apps card vs JSON/text fallback), and, importantly, that Dota 2 handles partial drafts with calibrated probabilities plus calibrated next-pick win rates while Deadlock/Marvel/LoL only return a probability for a complete roster and label partial-draft recommendations as empirical pair-data scores. It also specifies a citation/source_url presentation obligation. 'This tool is read-only' merely restates readOnlyHint=true, and nothing is said about rate limits or cost.

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: the core purpose and the 'when to use' sentence come first, then regime details, then args. The Args block largely restates schema fields and could be trimmed, but the prose is dense and nearly every sentence carries actionable 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 the returns paragraph is redundant but harmless; the essential gaps are covered, including the cross-client rendering difference and the per-game complete-roster constraints that would otherwise cause agents to misread a missing win rate. The only real hole is that the required `context` argument is never mentioned in the description and no alternative-tool routing is given.

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 adds real meaning beyond the schema: hero-count bounds per game (0-5 for Dota/LoL, 0-6 otherwise), that my_heroes may be empty for a fresh draft, and that my_side is Dota-only. It omits the required `context` parameter entirely, leaving that to the schema.

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+resource (analyze a draft, render a win-rate board) and immediately scopes it to draft, matchup, win-probability and next-pick questions across four named games. It also differentiates itself from siblings by saying it combines the existing prediction and recommendation tools, so an agent can tell it apart from predict_winrate and recommend_pick without opening either schema.

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 clear usage context ('use this for visual draft, matchup, win-probability, or next-pick questions') and per-game applicability rules. It does not say when to prefer the narrower siblings (predict_winrate, recommend_pick, get_matchup) instead, so the routing decision is only half-specified.

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