Atlas prints Invalid MCP URL for "<name>" because remoteURL() cannot parse the configured `url` on that remote MCP server, so connectRemote short-circuits before building any transport. Fix it by opening your Atlas config and making the `url` an absolute http:// or https:// URL, removing stray quotes, trailing commas, or unexpanded shell variables, then restarting Atlas and confirming the server reaches connected.
Why does Atlas say Invalid MCP URL
Atlas says Invalid MCP URL for "<name>" when remoteURL() cannot parse the `url` configured on that remote MCP server entry. connectRemote short-circuits at that point, having built 0 transports, which is why no connection attempt ever appears in the logs.
The Invalid MCP URL error in Atlas is a parse error, not a network error. remoteURL() never got as far as contacting anything. Nothing was dialed, no transport was constructed, and no timeout elapsed. That is useful information: the server itself is not implicated. The string in your config is. The most common offenders are a relative path instead of an absolute URL, a host name with no scheme, a value wrapped in extra quotes by a config editor, and an environment variable written into config as literal text that was never expanded. Atlas connects to Model Context Protocol servers and exposes their tools to the agent, but it has to be able to parse the address first.
How to fix an Invalid MCP URL in Atlas
Fix the Atlas Invalid MCP URL error in 4 steps: open your config and make the `url` on that mcp entry an absolute http:// or https:// URL, remove stray quotes and trailing commas and unexpanded shell variables, run `atlas mcp add <name> --url <url>` to have the CLI validate it, then restart Atlas.
Start by reading the raw `url` value character by character. It must be absolute and must carry an http:// or https:// scheme. `localhost:3000/mcp` will not parse. `https://localhost:3000/mcp` will. Then look for the packaging problems: a value quoted twice, a trailing comma that pulled a stray character into the string, or a `$MCP_HOST` style variable sitting in config as literal text because config files do not expand shell variables. If you would rather not hand-edit, `atlas mcp add <name> --url <url>` writes the entry for you and validates the value on the way in, throwing `Invalid URL: ...` on a bad one.
How to verify the MCP URL fix worked
Verify the Atlas MCP URL fix by restarting Atlas and confirming the server reaches connected. remoteURL() runs again at connect time, so a `url` that parses lets connectRemote build its 1st transport. A status row still reading Invalid MCP URL means the string in config is still unparseable.
Restarting Atlas is required, because remoteURL() is called on the connect path and the connect path runs at startup. Editing the config alone leaves the old error status in place. After the restart, check the server's status. Reaching connected means the URL parsed and the transport was built and accepted. Moving to a different error, such as failed or needs_auth, also means the URL parsed: you have cleared the Invalid MCP URL problem entirely and moved on to a separate one further down the connect path. Both outcomes confirm the fix landed.
Let atlas mcp add validate the MCP URL for you
Running `atlas mcp add <name> --url <url>` makes the Atlas CLI validate the URL before it writes 1 line to config. A bad value throws `Invalid URL: ...` immediately, at the command line, instead of surfacing later as an Invalid MCP URL status on a server that never connects.
Hand-editing config is where malformed URLs come from, so pushing the URL through `atlas mcp add <name> --url <url>` removes an entire class of error. The CLI parses the value you pass, rejects it up front with `Invalid URL: ...` if it cannot, and only writes the mcp entry when the URL is well formed. The feedback loop is immediate, which beats discovering the problem on the next Atlas startup. This is the recommended path when you are scripting Atlas setup or adding a remote MCP server on a new machine for the first time.
Why atlas mcp auth fails with the same Invalid MCP URL error
In Atlas, `atlas mcp auth` fails with Invalid MCP URL for "<name>" for the same reason the connection does: remoteURL() cannot parse the configured `url`, and connectRemote short-circuits after building 0 transports. Authentication cannot start against a server whose address Atlas cannot parse.
Users often try `atlas mcp auth <name>` after a failed connection, hoping the problem is a missing login. When the underlying error is Invalid MCP URL, the auth command produces the identical error, and for good reason. The OAuth flow needs a transport, the transport needs a parsed URL, and remoteURL() never produced one. Fix the `url` in config first. Once the URL parses and the server reaches connected, or moves to needs_auth, running `atlas mcp auth <name>` becomes meaningful. Until then it is the same short-circuit reported through a different command.
How to fix it
- 01Open your Atlas config and check the `url` on that mcp entry; it must be an absolute http:// or https:// URL.
- 02Remove stray quotes, trailing commas, or shell variables that were never expanded.
- 03Run `atlas mcp add <name> --url <url>` to let the CLI validate the URL for you (it throws `Invalid URL: ...` on a bad value).
- 04Restart Atlas and confirm the server reaches connected.
Frequently asked questions
- How do I fix Invalid MCP URL in Atlas?
- Open your Atlas config and make the `url` on that mcp entry an absolute http:// or https:// URL. Remove stray quotes, trailing commas, or unexpanded shell variables, then restart Atlas and confirm the server reaches connected.
- What causes the Invalid MCP URL error in Atlas?
- remoteURL() cannot parse the configured `url` for a remote MCP server, so connectRemote short-circuits before building any transport. It is a parse error in your config string, not a network failure.
- Does an Atlas MCP url need http:// or https://?
- Yes. The `url` on a remote mcp entry must be an absolute http:// or https:// URL. A bare host and port such as localhost:3000/mcp will not parse and produces Invalid MCP URL.
- How do I add an MCP server url in Atlas without breaking it?
- Run `atlas mcp add <name> --url <url>`. The Atlas CLI validates the URL for you and throws `Invalid URL: ...` on a bad value, instead of writing a broken entry that fails at the next startup.
- Why does atlas mcp auth also fail with Invalid MCP URL?
- Because the OAuth flow needs a transport, and connectRemote short-circuits before building one when remoteURL() cannot parse the `url`. Fix the URL in config first, then authentication becomes possible.
- Can I put an environment variable in the Atlas MCP url field?
- A shell variable written as literal text into config is never expanded, and remoteURL() will fail to parse it, producing Invalid MCP URL. Write the absolute http:// or https:// URL out in full.
- Do I need to restart Atlas after fixing an MCP url?
- Yes. remoteURL() runs on the connect path, which runs at startup. Restart Atlas after editing the `url` and confirm the server reaches connected.
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