lean_ctx/tools/registered/
shell_alias.rs

1use rmcp::ErrorData;
2use rmcp::model::Tool;
3use serde_json::{Map, Value, json};
4
5use crate::server::tool_trait::{McpTool, ToolContext, ToolOutput, get_str};
6use crate::tool_defs::tool_def;
7
8/// A `shell` tool alias that transparently delegates to `ctx_shell`'s compression
9/// logic. Registered for all MCP clients (see `server::registry`); it exists for
10/// clients (like Codex Desktop) whose agent model prefers a tool named `shell` /
11/// `bash` over `ctx_shell` and would otherwise fall back to a native, uncompressed
12/// shell tool.
13///
14/// This solves the "Codex Desktop doesn't compress" issue (#337): the Desktop app
15/// loads the MCP server but the agent ignores `ctx_shell` and uses its native
16/// `Bash` tool instead. By providing a `shell` tool with a familiar interface,
17/// the model naturally routes commands through our compression pipeline.
18pub struct ShellAliasTool;
19
20impl McpTool for ShellAliasTool {
21    fn name(&self) -> &'static str {
22        "shell"
23    }
24
25    fn tool_def(&self) -> Tool {
26        tool_def(
27            "shell",
28            "Shell command with auto-compression (~95 patterns). Alias for ctx_shell.\n\
29             Output is compressed for token savings. For verbatim output pass raw=true.\n\
30             Use when your MCP client prefers shell/bash over ctx_shell — transparently\n\
31             delegates to ctx_shell internals.",
32            json!({
33                "type": "object",
34                "properties": {
35                    "command": {
36                        "type": "string",
37                        "description": "Shell command"
38                    },
39                    "cwd": {
40                        "type": "string",
41                        "description": "Working dir"
42                    }
43                },
44                "required": ["command"]
45            }),
46        )
47    }
48
49    fn handle(
50        &self,
51        args: &Map<String, Value>,
52        ctx: &ToolContext,
53    ) -> Result<ToolOutput, ErrorData> {
54        let command = get_str(args, "command")
55            .ok_or_else(|| ErrorData::invalid_params("command is required", None))?;
56
57        if let Some(rejection) = crate::tools::ctx_shell::validate_command(&command) {
58            return Ok(ToolOutput::simple(rejection));
59        }
60
61        if let Err(msg) = crate::core::shell_allowlist::check_shell_allowlist(&command) {
62            return Ok(ToolOutput::simple(msg));
63        }
64
65        tokio::task::block_in_place(|| {
66            let cwd = get_str(args, "cwd");
67            let mut shell_args = Map::new();
68            shell_args.insert("command".to_string(), Value::String(command));
69            if let Some(dir) = cwd {
70                shell_args.insert("cwd".to_string(), Value::String(dir));
71            }
72            // raw=false → always compress (the whole point of this alias)
73            shell_args.insert("raw".to_string(), Value::Bool(false));
74
75            crate::tools::registered::ctx_shell::CtxShellTool.handle(&shell_args, ctx)
76        })
77    }
78}
lean_ctx/tools/registered/shell_alias.rs

lean_ctx/tools/registered/
shell_alias.rs
