DynoTable
Intermedio6 min de lectura

DynamoDB MCP for Codex

Codex can read your DynamoDB schema and query your tables once you give it a server to call. Codex configures MCP in TOML, not JSON, and that difference is where most setups die — the table name is mcp_servers, snake_case, and it is not the mcpServers key every other client uses.

This guide covers the config, the transport rule, the timeouts worth setting, and how to connect without putting AWS credentials in the agent's environment. For how the options compare, see the DynamoDB MCP server overview.

What Codex can do once it's connected

  • Read your real schema — tables, key schema, indexes, and the attributes that actually appear in items.
  • Run queries — Query, Scan, GetItem and PartiQL against live data, so it can verify its own assumptions.
  • Aggregate — counts and group-bys DynamoDB can't do natively.
  • Propose edits — into a reviewable staging area, not into your table.

Before you start

  1. Install DynoTable — download it and add the AWS profile Codex should see.
  2. Turn the MCP server on — Settings → MCP Server. Off by default, bound to 127.0.0.1.
  3. Expose a profile — its MCP section → Expose via MCP. The connection is hard-bound to that profile's credentials and region.

Copy the endpoint and real port from that pane.

Add the server to config.toml

Codex reads MCP servers from ~/.codex/config.toml:

[mcp_servers.dynotable-prod]
url = "http://127.0.0.1:<port>/mcp?profile=prod"

That's the whole entry. Three details decide whether it works:

The table is mcp_servers — snake_case. Not mcpServers. Codex silently ignores a table it doesn't recognize, so a camelCase key produces no error and no server. If your config looks right and Codex sees nothing, check this first.

url selects the transport. Codex picks the transport from which key is present: command means stdio, url means streamable HTTP. They are mutually exclusive — url, bearer_token_env_var and http_headers cannot sit in a table that also has command. DynoTable is HTTP, so url only.

?profile=prod is a hint, not authorization. It pre-selects the profile in DynoTable's approval prompt; you still approve the connection in the app.

Optional knobs worth setting

[mcp_servers.dynotable-prod]
url = "http://127.0.0.1:<port>/mcp?profile=prod"
startup_timeout_sec = 30
tool_timeout_sec = 60
enabled = true

tool_timeout_sec is the one that matters for DynamoDB. A Scan over a large table can outlast a short default and surface as a tool error rather than as the slow query it actually is. If Codex reports timeouts on big tables, raise this before assuming the connection is broken.

enabled = false is a clean way to park a server without deleting the block.

Project-scoped config

Codex also reads .codex/config.toml from a project directory, for trusted projects. Don't put a loopback server there if the repo is shared — the port is per-machine and your teammates don't run DynoTable. Keep this one in ~/.codex/config.toml.

Approve the connection

On first connect, DynoTable shows a consent prompt naming the client and asking for a scope:

  • Read only — schema, queries, item reads. No changes.
  • Read & stage — plus staging changes for you to review. Never a direct write.
  • Full access — plus opening views, filters and exports. Writes still go through staging.

Start at Read only. Scope is re-checked on every call, so narrowing takes effect immediately.

Verify it actually loaded

Restart Codex after editing config.toml — it reads the file at startup, so an edit mid-session changes nothing. Then ask for something only your data answers: "list the tables in this profile and their key schemas."

A hedged, generic answer means the tools never loaded. Work the checklist below.

Why not give Codex AWS credentials?

The standard pattern — an MCP server holding an AWS access key and secret — hands the agent's process the full IAM power of those keys, with no DynamoDB-specific review step.

The risk isn't a malicious model. It's that an MCP tool result is untrusted input: a row, a document or a fetched page can carry instructions. That's , and against a write-capable server holding your keys it acts on your tables directly.

Through DynoTable:

  • Your AWS credentials never reach the agent. DynoTable holds the profiles and makes the calls; nothing in the Codex process can read a key.
  • There is no direct write tool. Not gated — absent. At Read & stage the worst outcome is a diff card you review.

Troubleshooting

Codex doesn't see the server at all. In order: is the table named mcp_servers (snake_case), did you restart Codex after editing, and is the TOML valid?

Server defined but not starting. Check for a command key in the same table as url — they're mutually exclusive. Also confirm enabled isn't false.

Connects, then times out on queries. Raise tool_timeout_sec. A large Scan is slow, not broken.

Connected, zero tools. No profile exposed in DynoTable, or the connection was approved at a scope exposing nothing you asked for.

Edits didn't change DynamoDB. Expected — they're staged. Commit them from the staging area.

FAQ

How do I connect Codex to DynamoDB?

Install DynoTable, turn on its MCP server under Settings → MCP Server, expose the AWS profile you want Codex to see, then add an [mcp_servers.dynotable] table to ~/.codex/config.toml with a url pointing at the endpoint from that pane. Restart Codex and approve the connection in DynoTable at the scope you want.

Where does Codex configure MCP servers?

In ~/.codex/config.toml, using one TOML table per server named [mcp_servers.dynotable]. Codex also reads .codex/config.toml from a trusted project directory, but a loopback server belongs in the home-directory file because the port is per-machine.

Why doesn't Codex see my MCP server in config.toml?

The most common cause is the table name: it must be mcp_servers in snake_case, not mcpServers. Codex ignores an unrecognized table without an error. The next two causes are editing the file without restarting Codex, and putting a url key in a table that also has command.

Does Codex use url or command for a remote MCP server?

Use url for a streamable HTTP server like DynoTable. Codex selects the transport from which key is present — command means stdio, url means HTTP — and the two cannot appear in the same table.

Can Codex write to my DynamoDB tables?

Not directly, through DynoTable — there is no commit tool to call. At Read & stage or Full access the agent stages a change, it appears as a reviewable diff in the app, and it is written only when you commit it. A community MCP server holding write-capable AWS keys can write directly.

Product names are trademarks of their respective owners; referenced for identification only. Codex config format verified 2026-07-27.

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