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

Annotations already declare readOnly and openWorld, so the safety profile is covered; the description adds the genuinely useful caveat 'Player stats can be absent right after a match', which an agent cannot infer from annotations or schema. It stops short of describing pagination or error behavior for invalid ids.

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?

Purpose is front-loaded, but the long middle clause is an inventory of return fields (agents, rating, ACS, K/D/A, KAST, ADR, headshot percent, first kills/deaths) that duplicates what the output schema already carries. The valuable sentences — the missing-stats caveat and the id sources — are buried at the end.

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?

Since an output schema exists, the return-value enumeration is redundant but not harmful; what matters is covered — how to obtain the id, what the call resolves to, and the one data-quality gotcha. Nothing blocking remains for a single-parameter lookup.

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% and the single parameter already documents itself as a required numeric VLR match id sourced from vlr_matches/vlr_results. The description's 'numeric id' plus id-source sentence largely restates the schema, adding no format or validation detail beyond it, so 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 ('Returns one VLR.gg Valorant match by numeric id') and enumerates the scope of the returned record (event, stage, maps, per-player lines, H2H, recent results). An agent can immediately tell this is the single-match detail endpoint distinct from vlr_matches or vlr_results.

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?

Explicitly tells the agent where to get ids ('Get ids from vlr_matches, vlr_results or vlr_event_matches'), which is the real precondition for calling it. It does not spell out when to prefer sibling detail tools like vlr_match_economy or vlr_match_rounds, so the when-not side is only implied.

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