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horizOn MCP Server

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by ProjectMakersDE
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TypeScript
Remote

Decline Match Invitation

horizon_decline_match_invite
DestructiveIdempotent

Declines a match invitation at its exact original revision, letting a player reject a reviewed invite without silently substituting a newer state.

Instructions

Executes decline match invitation under the exact original revision. Use when: explicit asynchronous multiplayer actions after reading horizon://docs/matches. Not for: automatic polling, page traversal, timeout progression, invented winners or automatic rewards. Reconcile with horizon_get_matches and horizon_get_match. Consent and game consensus do not validate honest gameplay. Requires: userId and the player's session: sign in with horizon_signin_email or horizon_signin_anonymous and pass its accessToken as sessionToken. Side effects: One HTTP attempt. Start requires the creator and every joined UUID exactly once. Turn requires the current unexpired actor. Timeout advances only one turn. Active leave forfeits without selecting a winner. Lobby cancel is creator-only. Full Inbox retains a durable notice without undoing a committed move. Returns: {match,pollAfterSeconds,serverTime}; departing lobby actors receive metadata only and lose point-read access. Errors: 404 hides private/missing/expired matches. 409 REVISION_CONFLICT or STATE_CONFLICT: explicitly reread and reconcile the original intent, never replace the revision or automatically resubmit. RESULT_CONFLICT preserves the original report. RUN_EXPIRED/RUN_ALREADY_USED never allow replacement ranked runs. 501 FEATURE_NOT_SUPPORTED is explicit for simpleServer ranked mode. 401 means the session is missing or expired: sign in again and retry with the new accessToken. 403 for a session means the token belongs to another user: pass the userId that signed in. Needs HORIZON_API_KEY. Every failure returns an error result (isError) with the HTTP status and body: a 401 that horizon_test_connection also returns means HORIZON_API_KEY is wrong, 429 means the account's per-minute rate limit was reached (wait a minute, then retry).

Input Schema

NameRequiredDescriptionDefault
userIdYesActive player matching the session and project
matchIdYesOriginal server match UUID in the selected project
sessionTokenYesPlayer accessToken sent only as Bearer
expectedRevisionYesOriginal reviewed revision; never substitute a newer revision after an uncertain write

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv1.9.1

TDQS

A3.5/5.0
Behavior4/5

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

Beyond the annotations, the description discloses auth requirements, one HTTP attempt, revision-conflict behavior, 404/409/401/403/429 handling, and rate-limit semantics. Some listed side effects belong to other match operations, but the tool’s failure and concurrency behavior is unusually well documented.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness2/5

Is the description appropriately sized, front-loaded, and free of redundancy?

It is structured with Use/Side effects/Returns/Errors headings, but it is far too long for one operation. Large portions describe start, turn, timeout, active leave, lobby cancel, inbox, and ranked-run behavior that is irrelevant to declining a match invitation.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The return shape and error/auth behavior are described, which matters because there is no output schema. However, the definition does not clearly explain the core effect of declining an invitation or the resulting match state, and it substitutes broad match-lifecycle material for focused semantics.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is already 100%, so the baseline is 3, but the description adds meaningful auth context for sessionToken and userId by explaining the sign-in flow and passing accessToken as sessionToken. It also reinforces the expectedRevision rule, though matchId itself is not elaborated.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The first sentence states a specific verb and resource, 'decline match invitation,' and adds the key constraint 'under the exact original revision.' It is clear enough to identify the action, but it does not distinguish this tool from adjacent invitation-decline or match-lifecycle siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives some usage guidance via 'Use when' and 'Not for,' but those apply broadly to asynchronous multiplayer actions rather than specifically to declining a match invitation. It names horizon_get_matches and horizon_get_match for reconciliation, yet does not explicitly say when to decline versus accept, leave, or cancel.

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

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