> ## Documentation Index
> Fetch the complete documentation index at: https://gofastmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# client

# `fastmcp.cli.client`

Client-side CLI commands for querying and invoking MCP servers.

## Functions

### `resolve_server_spec` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/cli/client.py#L42" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
resolve_server_spec(server_spec: str | None) -> str | dict[str, Any] | ClientTransport
```

Turn CLI inputs into something `Client()` accepts.

Exactly one of `server_spec` or `command` should be provided.

Resolution order for `server_spec`:

1. URLs (`http://`, `https://`) — passed through as-is.
   If `--transport` is `sse`, the URL is rewritten to end with `/sse`
   so `infer_transport` picks the right transport.
2. Existing file paths, or strings ending in `.py`/`.js`/`.json`.
3. Anything else — name-based resolution via `resolve_name`.

When `command` is provided, the string is shell-split into a
`StdioTransport(command, args)`.

### `coerce_value` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/cli/client.py#L263" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
coerce_value(raw: str, schema: dict[str, Any]) -> Any
```

Coerce a string CLI value according to a JSON-Schema type hint.

### `parse_tool_arguments` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/cli/client.py#L297" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
parse_tool_arguments(raw_args: tuple[str, ...], input_json: str | None, input_schema: dict[str, Any]) -> dict[str, Any]
```

Build a tool-call argument dict from CLI inputs.

A single JSON object argument is treated as the full argument dict.
`--input-json` provides the base dict; `key=value` pairs override.
Values are coerced using the tool's `inputSchema`.

### `format_tool_signature` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/cli/client.py#L369" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
format_tool_signature(tool: mcp.types.Tool) -> str
```

Build `name(param: type, ...) -> return_type` from a tool's JSON schemas.

### `list_command` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/cli/client.py#L625" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
list_command(server_spec: Annotated[str | None, cyclopts.Parameter(help='Server URL, Python file, MCPConfig JSON, or .js file')] = None) -> None
```

List tools available on an MCP server.

**Examples:**

fastmcp list [http://localhost:8000/mcp](http://localhost:8000/mcp)
fastmcp list server.py
fastmcp list mcp.json --json
fastmcp list --command 'npx -y @mcp/server' --resources
fastmcp list [http://server/mcp](http://server/mcp) --transport sse

### `call_command` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/cli/client.py#L774" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
call_command(server_spec: Annotated[str | None, cyclopts.Parameter(help='Server URL, Python file, MCPConfig JSON, or .js file')] = None, target: Annotated[str, cyclopts.Parameter(help='Tool name, resource URI, or prompt name (with --prompt)')] = '', *arguments: str) -> None
```

Call a tool, read a resource, or get a prompt on an MCP server.

By default the target is treated as a tool name. If the target
contains `://` it is treated as a resource URI. Pass `--prompt`
to treat it as a prompt name.

Arguments are passed as key=value pairs. Use --input-json for complex
or nested arguments.

**Examples:**

```
fastmcp call server.py greet name=World
fastmcp call server.py resource://docs/readme
fastmcp call server.py analyze --prompt data='[1,2,3]'
fastmcp call http://server/mcp create --input-json '{"tags": ["a","b"]}'
```

### `discover_command` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/cli/client.py#L875" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
discover_command() -> None
```

Discover MCP servers configured in editor and project configs.

Scans Claude Desktop, Claude Code, Cursor, Gemini CLI, Goose, and
project-level mcp.json files for MCP server definitions.

Discovered server names can be used directly with `fastmcp list`
and `fastmcp call` instead of specifying a URL or file path.

**Examples:**

fastmcp discover
fastmcp discover --source claude-code
fastmcp discover --source cursor --source gemini --json
fastmcp list weather
fastmcp call cursor:weather get\_forecast city=London