Injected parameters and metadata
Why injection exists
Creators often do not fully control the downstream MCP surface end users hit—for example hosted MCP bridges or integration platforms where wiring tool parameters is easy but reading custom HTTP headers is awkward or impossible. Identity and context (user id, anonymous state, portal links, merge hints, etc.) still need to reach your server without putting those fields in the upstream tool schema for the host model to fill, so users are not prompted for userId-style inputs or secrets.
Agentsyx therefore auto-injects context in two ways: always (headers, and for MCP downstream a small mirrored set in JSON-RPC arguments) and optionally (per-parameter tags you configure on the downstream connector in Creator). The goal is the same in both cases: convenience, values hidden from the host, and no dependency on header access when the integration cannot use them cleanly.
Always injected (every downstream tool call)
On each proxied tools/call to your downstream URL, Agentsyx attaches platform context derived from auth, billing, and anonymous usage.
- HTTP headers — Primary channel. Use the documented
x-a6-*(and related) headers described in Inputs to downstream servers. This is the uniform contract for any downstream (custom MCP server, OpenAPI, etc.). - MCP downstream: mirrored
arguments— For connectors whose downstream interface is MCP, Agentsyx may also merge a small subset of the same ideas intoparams.argumentswhen values are present—for example anonymous short id, whether the caller is anonymous, portal URL, and login URL—so tools-only setups (e.g. some Zapier MCP flows) can map inputs without reading headers. Other context (such as anonymous subscription flag, canonical user UUID, username/email, merged prior user ids) is delivered on headers unless you add optional tagging (below).
Billing and plan enforcement remain upstream; injected values are for attribution and UX, not a substitute for platform billing proof.
Optional injection (downstream connector configuration)
In Agentsyx Creator, open your downstream connector, import the tool schema from your MCP or OpenAPI source, then use Parameter Tagging on each tool: for each parameter you can assign a tag such as User Name, User Email, User Id, or Subscription Plan.
- Effect: Tagged parameters are removed from the schema published upstream (the host model does not see them) and are filled at execution time with the correct value for the current user or subscription context.
- Reason: Same as above—you keep your downstream argument names (e.g.
userId) while the platform supplies the value, without exposing that slot to the host and without requiring header reads in constrained integrations. - Rules: Typically one parameter per tag per tool; if a tag is already used on another parameter, Creator prevents double assignment.
| Creator tag label | Injected meaning (plain language) |
|---|---|
| User Name | Display name for the current end user |
| User Email | Email for the current end user |
| User Id | Platform user id (UUID) for the caller |
| Subscription Plan | Current subscription / plan label |
For registering integrations as downstream connectors, see Integration platforms and Understanding Connectors.
MCP params._meta (optional)
MCP allows an optional _meta object on params (next to name and arguments). Hosts may attach vendor-specific metadata there. On the downstream hop, do not depend on particular _meta keys for platform identity or billing; prefer x-a6-* headers and optional tagged arguments as above. Tools and resources may still carry your own _meta from definitions or the host—what appears varies by client and proxy.
For anonymous lifecycle and merge semantics at a product level, see Anonymous and unauthenticated users.