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horizOn MCP Server

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by ProjectMakersDE
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TypeScript
Remote

cancel group invite

horizon_cancel_group_invite
DestructiveIdempotent

Cancels a pending group invitation after explicit confirmation, using the reviewed revision and exact requestId; no automatic retry on uncertainty.

Instructions

Applies the explicit cancel group invite action using the reviewed group revision. Use when: the player explicitly confirms this group action. Not for: replacing reviewed revisions/request IDs, bypassing a leader's block, or retrying automatically after uncertainty. Requires: userId and the player's session: sign in with horizon_signin_email or horizon_signin_anonymous and pass its accessToken as sessionToken. Current group revision and the exact pending requestId where applicable. Side effects: Leader/officer cancels this exact invitation. No automatic retry. Same-revision replay cannot create a second effect. Returns: {groups:MyGroupsView,group:GroupView|null}. groups is the actor's complete snapshot, never the target's private state. group is null after leave/delete; nonmembers never receive private data. Replace only the matching host/project/player cache. Errors: Use horizon_get_groups and horizon_get_group_pending to reconcile state. 409 REVISION_CONFLICT or uncertain response: read and reconcile intent, never refresh the revision and repeat automatically. Pending decisions require the original requestId; REQUEST_NOT_FOUND means it was removed/replaced. INBOX_FULL rolls back the entire action. 403 rejects group role, session or bilateral block violations. 429 is reported without automatic retry. 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
userIdYesSigned-in player matching the Bearer session
groupIdYesExact group UUID in the current project; never an authorization credential
requestIdYesExact pending identity from the reviewed snapshot
sessionTokenYesPlayer accessToken, sent only in Authorization
targetUserIdYesOther player in this project
expectedRevisionYesExact reviewed revision; never replace automatically after an uncertain response

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv1.9.1

TDQS

A4.2/5.0
Behavior5/5

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

Adds substantial context beyond the annotations: it names the required sign-in flow (horizon_signin_email / horizon_signin_anonymous → sessionToken), the exact side effect (leader/officer cancels this invitation), the no-auto-retry policy, the idempotency mechanism (same-revision replay cannot create a second effect), and cache invalidation scope. Error semantics (409 REVISION_CONFLICT, REQUEST_NOT_FOUND, INBOX_FULL rollback, 403 role/block, 429 rate limit, 401/403 session cases) are all disclosed.

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

Conciseness3/5

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

Front-loads the action, then when/when-not, requirements, side effects, returns, and errors in a sensible order. However it bloats: the final sentence re-explains the 401 and 429 meanings already given in the preceding error block, and the returns/cache sentence is compressed past readability.

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

Completeness5/5

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

For a destructive, open-world, six-required-parameter mutation with no output schema, the description covers auth sourcing, side effects, return shape, cache replacement scope, and the full failure/reconciliation protocol. Nothing material needed to invoke it correctly is missing.

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; the description earns above that by explaining the semantics of expectedRevision and requestId in relation to error codes (revision conflicts, REQUEST_NOT_FOUND meaning the request was removed/replaced) rather than just restating field types.

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?

States a specific verb and resource ('cancel group invite action using the reviewed group revision') and clarifies the actor ('Leader/officer cancels this exact invitation'). It does not, however, disambiguate from the closest siblings — horizon_decline_group_invite and horizon_cancel_group_request — so an agent must infer which cancel path applies.

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

Usage Guidelines4/5

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

Explicit 'Use when: the player explicitly confirms this group action' plus a 'Not for' clause excluding revision replacement, block bypass, and automatic retry. It also routes to horizon_get_groups and horizon_get_group_pending for reconciliation, but never explains why to pick this over decline/cancel_request siblings.

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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