lean_ctx_server/tools/registered/
shell_alias.rs

1// SPDX-License-Identifier: Apache-2.0
2use rmcp::ErrorData;
3use rmcp::model::Tool;
4use serde_json::{Map, Value, json};
5
6use crate::server::tool_trait::{McpTool, ToolContext, ToolOutput, get_str};
7use lean_ctx::tool_defs::tool_def;
8
9/// A `shell` tool alias that transparently delegates to `ctx_shell`'s compression
10/// logic. Registered for all MCP clients (see `server::registry`); it exists for
11/// clients (like Codex Desktop) whose agent model prefers a tool named `shell` /
12/// `bash` over `ctx_shell` and would otherwise fall back to a native, uncompressed
13/// shell tool.
14///
15/// This solves the "Codex Desktop doesn't compress" issue (#337): the Desktop app
16/// loads the MCP server but the agent ignores `ctx_shell` and uses its native
17/// `Bash` tool instead. By providing a `shell` tool with a familiar interface,
18/// the model naturally routes commands through our compression pipeline.
19pub struct ShellAliasTool;
20
21impl McpTool for ShellAliasTool {
22    fn name(&self) -> &'static str {
23        "shell"
24    }
25
26    fn rights_name(&self) -> &'static str {
27        "ctx_shell"
28    }
29
30    fn tool_def(&self) -> Tool {
31        tool_def(
32            "shell",
33            "Shell command with auto-compression (~95 patterns). Alias for ctx_shell.\n\
34             Output is compressed for token savings. Big logs: narrow the command (grep, sed -n, head/tail).\n\
35             Use when your MCP client prefers shell/bash over ctx_shell — transparently\n\
36             delegates to ctx_shell internals.",
37            json!({
38                "type": "object",
39                "properties": {
40                    "command": {
41                        "type": "string",
42                        "description": "Shell command"
43                    },
44                    "cwd": {
45                        "type": "string",
46                        "description": "Working dir"
47                    },
48                    "raw": {
49                        "type": "boolean",
50                        "description": "Exact bytes, uncompressed; only for diffs to apply, hashes, encoded output. Default false."
51                    }
52                },
53                "required": ["command"]
54            }),
55        )
56    }
57
58    fn handle(
59        &self,
60        args: &Map<String, Value>,
61        ctx: &ToolContext,
62    ) -> Result<ToolOutput, ErrorData> {
63        let command = get_str(args, "command")
64            .ok_or_else(|| ErrorData::invalid_params("command is required", None))?;
65
66        // #1811: the write-doctrine check is deliberately NOT repeated here.
67        // It judges where a relative redirect target lands, and only the
68        // delegate below knows that — it resolves the requested `cwd` through
69        // the project-root jail before deciding. Judging the raw argument here
70        // would answer for a directory the command may never run in, and a
71        // second copy of the rule is a second answer waiting to drift from the
72        // first. The delegate refuses, with its own message, before executing.
73        if let Err(msg) = lean_ctx_shell_policy::check_shell_allowlist(&command) {
74            return Ok(ToolOutput::simple(msg.to_string()));
75        }
76
77        tokio::task::block_in_place(|| {
78            let cwd = get_str(args, "cwd");
79            // Compressed by default (the point of this alias), but honor an explicit
80            // raw=true so clients restricted to "shell"/"bash" still have the verbatim
81            // escape the description advertises — no MCP-specific tool required.
82            let raw = args.get("raw").and_then(Value::as_bool).unwrap_or(false);
83            let mut shell_args = Map::new();
84            shell_args.insert("command".to_string(), Value::String(command));
85            if let Some(dir) = cwd {
86                shell_args.insert("cwd".to_string(), Value::String(dir));
87            }
88            shell_args.insert("raw".to_string(), Value::Bool(raw));
89
90            crate::tools::registered::ctx_shell::CtxShellTool.handle(&shell_args, ctx)
91        })
92    }
93}
lean_ctx_server/tools/registered/shell_alias.rs

lean_ctx_server/tools/registered/
shell_alias.rs
