Merge Agent Handler vs StackOne

Merge Agent Handler

Agent Handler's access keys can be limited to named users, tool packs and a runtime scope, with an expiry, and an agent can create an account with one documented request. No rate limit figures are published, Pro starts at $1,000 a month with no published overage rate, and failed or blocked calls spend credits.

StackOne

StackOne's MCP server signs each person in with OAuth, lets them grant individual accounts and actions, and by default exposes two search and execute tools in place of the full catalogue. Session token URLs carry the credential in the query string for a year by default, and the Consumption Schedule and pricing page disagree on whether failed calls are billed.

Merge Agent Handler

1. Call search_tools with a plain-language intent before tools/list. A Tool Pack can hold hundreds of tools and Slack alone lists 50
2. Add ?connectors=slack to the MCP URL to limit a connection to named connectors, and ?paginated=true only if the client follows nextCursor
3. Carry a user-scoped key with runtime:all only. The production key reaches every Registered User and the management endpoints
4. On reauth_required read data.reauth_reason, then call authenticate_<connector> by name. Intent search doesn't return the authenticate tools
5. Pin MCP-Protocol-Version to 2025-03-26 when context is tight. Later revisions repeat object results in structuredContent

StackOne

1. Send Accept: application/json,text/event-stream on every MCP request to https://api.stackone.com/mcp, by POST only. Without it the server answers 406
2. In search_execute mode call {provider}_search_actions first and pass the returned action_id to {provider}_execute_action. Never hardcode action ids
3. Pass the API key as the Basic auth username with an empty password, and name the linked account in x-account-id
4. On 429 or 408 wait the seconds given in Retry-After. StackOne has already retried a provider's 429 up to five times within a 60-second request lifetime
5. On 412 read errorCode and details.statusReasons. AccountErrorStatus needs a person to re-authenticate the linked account