[CodeCompanion] Error: Couldn't decode the tool arguments (when project_root is empty?)

[Picalines]

Hi! Tried to follow the setup instructions for CodeCompanion plugin, but I get the error when an agent tries to use @{vectorcode_ls} or @{vectorcode_files_ls} tools

Here's a part of codecompanion debug output where I asked a model just to run @{vectorcode_files_ls} without other instructions

local settings = {
  model = "claude-3-7-sonnet", 
  extended_output = false,
  extended_thinking = true,
  thinking_budget = 16000,
  max_tokens = 17000,
  temperature = 0,
  top_p = nil,
  top_k = nil,
  stop_sequences = nil,
}

local messages = 
{ {
    content = "<system prompt>",
    cycle = 1,
    id = 126646444,
    opts = {
      tag = "from_config",
      visible = false
    },
    role = "system"
  }, {
    content = "Try to run vectorcode_files_ls command",
    cycle = 1,
    id = 29660827,
    opts = {
      visible = true
    },
    role = "user"
  }, {
    content = "I'll run the `vectorcode_files_ls` command to list files in the current project:",
    cycle = 1,
    id = 368175756,
    opts = {
      visible = true
    },
    reasoning = {
      content = "The user is asking me to run the `vectorcode_files_ls` command. This command retrieves a list of files that have been added to the database for a given project. Looking at the function definition, I can see it has one parameter:\n\n- `project_root`: The project for which the indexed files will be listed. This parameter is optional, and if left empty, it will default to the current project.\n\nSince the user didn't specify a particular project, I'll run the command for the current project by leaving the `project_root` parameter empty."
    },
    role = "llm"
  }, {
    cycle = 1,
    id = 137869998,
    opts = {
      visible = false
    },
    role = "llm",
    tool_calls = { {
        _index = 2,
        ["function"] = {
          arguments = "",
          name = "vectorcode_files_ls"
        },
        id = "toolu_01Upx2WKkvFBgTZ542ogY4Tn",
        type = "function"
      } }
  }, {
    content = {
      content = 'You made an error in calling the vectorcode_files_ls tool: "...on.nvim/lua/codecompanion/strategies/chat/tools/init.lua:168: Expected value but found T_END at character 1"',
      is_error = false,
      tool_use_id = "toolu_01Upx2WKkvFBgTZ542ogY4Tn",
      type = "tool_result"
    },
    cycle = 1,
    id = 631857839,
    opts = {
      visible = true
    },
    role = "tool"
  }, {
    content = {
      content = "<path>nvim/init.lua</path>",
      is_error = false,
      tool_use_id = "toolu_01Upx2WKkvFBgTZ542ogY4Tn",
      type = "tool_result"
    },
    cycle = 1,
    id = 1872022500,
    opts = {
      visible = true
    },
    role = "tool"
  }, {
  --- ... rest of files the vectorcode seemed to return

Which results in this error messages:

Couldn't decode the tool arguments: 
Error executing vim.schedule lua callback: ...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:197: Expected value but found T_END at character 1
stack traceback:
	[C]: in function 'decode'
	...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:197: in function <...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:141>
	vim/shared.lua: in function 'tbl_map'
	...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:141: in function 'form_messages'
	.../nvim/lazy/codecompanion.nvim/lua/codecompanion/http.lua:95: in function 'request'
	...ompanion.nvim/lua/codecompanion/strategies/chat/init.lua:929: in function <...ompanion.nvim/lua/codecompanion/strategies/chat/init.lua:848>

My suspicion is that it's something to do with how vectorcode_files_ls is called with arguments = "" (see above), but I lack enough context to be sure

vectorcode executable is installed with mason.nvim, CLI works normal. The agent did successfully ran the vectorize tool, but it consistently fails on ls or files ls

Might be some issue with codecompanion itself. I use version = '*' both for codecompanion and vectorcode integration plugin

[Davidyz]

Have you run into similar errors with other tools? I think the files_ls failure is due to the argument being an empty string and vim.json.decode in the anthropic adapter isn't happy about this. This tool only takes an optional parameter, so it's valid for the LLM to call the tool without a parameter. I think this should be handled in codecompanion.nvim anthropic adapter.

As for the ls tool, it's supposed to have no params, so I'm not sure why it's throwing errors. It'd be helpful if you could show me the debug info that contains a tool call to the vectorcode_ls tool.

[Picalines]

t'd be helpful if you could show me the debug info that contains a tool call to the vectorcode_ls tool.

Here's the output:

local settings = {
  model = "claude-sonnet-4", 
  extended_output = false,
  extended_thinking = true,
  thinking_budget = 16000,
  max_tokens = 17000,
  temperature = 0,
  top_p = nil,
  top_k = nil,
  stop_sequences = nil,
}

local messages = 
{ {
    content = "<system prompt>",
    cycle = 1,
    id = 126646444,
    opts = {
      tag = "from_config",
      visible = false
    },
    role = "system"
  }, {
    content = "Try to run vectorcode_ls tool",
    cycle = 1,
    id = 124559635,
    opts = {
      visible = true
    },
    role = "user"
  }, {
    content = "I'll run the vectorcode_ls tool to retrieve the list of accessible projects.",
    cycle = 1,
    id = 2119622141,
    opts = {
      visible = true
    },
    reasoning = {
      content = "The user wants me to run the vectorcode_ls tool. Looking at the function definition, it's used to retrieve a list of projects accessible via the VectorCode tools. The function doesn't require any parameters, so I can call it directly."
    },
    role = "llm"
  }, {
    cycle = 1,
    id = 10860277,
    opts = {
      visible = false
    },
    role = "llm",
    tool_calls = { {
        _index = 2,
        ["function"] = {
          arguments = "",
          name = "vectorcode_ls"
        },
        id = "toolu_014F7tcKc53pj4XCJzoaDMUa",
        type = "function"
      } }
  }, {
    content = {
      content = 'You made an error in calling the vectorcode_ls tool: "...on.nvim/lua/codecompanion/strategies/chat/tools/init.lua:168: Expected value but found T_END at character 1"',
      is_error = false,
      tool_use_id = "toolu_014F7tcKc53pj4XCJzoaDMUa",
      type = "tool_result"
    },
    cycle = 1,
    id = 179102148,
    opts = {
      visible = true
    },
    role = "tool"
  }, {
    content = {
      content = "<collection>~/Repos/dotfiles</collection>",
      is_error = false,
      tool_use_id = "toolu_014F7tcKc53pj4XCJzoaDMUa",
      type = "tool_result"
    },
-- ... rest of the collections it found ...

Error stack seems same but just in case:

Couldn't decode the tool arguments: 
Error executing vim.schedule lua callback: ...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:197: Expected value but found T_END at character 1
stack traceback:
	[C]: in function 'decode'
	...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:197: in function <...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:141>
	vim/shared.lua: in function 'tbl_map'
	...ecompanion.nvim/lua/codecompanion/adapters/anthropic.lua:141: in function 'form_messages'
	.../nvim/lazy/codecompanion.nvim/lua/codecompanion/http.lua:95: in function 'request'
	...ompanion.nvim/lua/codecompanion/strategies/chat/init.lua:929: in function <...ompanion.nvim/lua/codecompanion/strategies/chat/init.lua:848>

[Davidyz]

It looks like it's a codecompanion issue (as in, vim.json.decode throws an error when the "json encoded string" is an empty string). I'll open an issue over there.

[Davidyz]

Hi, since I don't have anthropic API access, would you be able to help test this PR?

[bnwa]

I'm also having the same issue:

  }, {
    cycle = 1,
    id = 530700211,
    opts = {
      visible = false
    },
    role = "llm",
    tool_calls = { {
        _index = 2,
        ["function"] = {
          arguments = "",
          name = "vectorcode_ls"
        },
        id = "toolu_01TH86Z9E61NGxRdruGw1xyc",
        type = "function"
      } }
  }, {
    content = {
      content = 'You made an error in calling the vectorcode_ls tool: "...on.nvim/lua/codecompanion/strategies/chat/tools/init.lua:171: Expected value but found T_END at character 1"',
      is_error = false,
      tool_use_id = "toolu_01TH86Z9E61NGxRdruGw1xyc",
      type = "tool_result"
    },
    cycle = 1,
    id = 766510302,
    opts = {
      visible = true
    },
    role = "tool"
  }, {
    content = {
      content = "Error calling `vectorcode_ls`",
      is_error = false,
      tool_use_id = "toolu_01TH86Z9E61NGxRdruGw1xyc",
      type = "tool_result"
    },
    cycle = 1,
    id = 1508412513,
    opts = {
      visible = true
    },
    role = "tool"
  } }

[Davidyz]

Are you also using anthropic adapter? I believe this is an adapter bug, and if this isn't anthropic please lmk so that we can fix it altogether.

[Davidyz]

Here's my patch trying to fix this for anthropic adapter. Please give it a try and lmk if it works for you.

[bnwa]

Are you also using anthropic adapter? I believe this is an adapter bug, and if this isn't anthropic please lmk so that we can fix it altogether.

Yes. It's definitely something to do with CodeCompanion's Anthropic adapter as you stated earlier. Your PR addresses the issue. Thank you for your time on this, it's appreciated.

[bnwa]

I'd setup custom tools using the VectorCode plugin for Avante.nvim, mimicking the tools in your plugin, and it doesn't have any of the issues.

[Picalines]

@Davidyz I tried your PR, now it throws another error

Error 400: {"type":"error","error":{"type":"invalid_request_error","message":"messages.1.content.1.tool_use.input: Input should be a valid dictionary"}}
Error: {
  body = '{"type":"error","error":{"type":"invalid_request_error","message":"messages.1.content.1.tool_use.input: Input should be a valid dictionary"}}',
  exit = 0,
  headers = { ... },
  status = 400
}

Here's a part of debug buffer

  }, {
    cycle = 1,
    id = 867854911,
    opts = {
      visible = false
    },
    reasoning = {
      content = "The user is asking me to use the vectorcode_ls tool. Looking at the function definition, this tool \"Retrieve a list of projects accessible via the VectorCode tools\" and doesn't require any parameters. I should call this tool to see what projects are available."
    },
    role = "llm",
    tool_calls = { {
        _index = 1,
        ["function"] = {
          arguments = "",
          name = "vectorcode_ls"
        },
        id = "toolu_017XqWpB5DZXEbD1Ha2yoQuC",
        type = "function"
      } }
  }, {

So my guess is that the Anthropic API expects something different (maybe just {})? Also unsure why @bnwa reported the fix have worked for them

[bnwa]

@Davidyz Apologies, @Picalines experience is reproducible for me as I'd forgotten to specify the branch in my plugin manager, only your fork.

[Davidyz]

Just made some new changes to make sure it sends an empty dict.

[Picalines]

@Davidyz seems to be working, thanks! I tried all tools and got OK results

I think the PR is ready for review then. Again, big thanks!

[Davidyz]

I actually wanted to play around with the tests and see if other adapters suffer from this too. Since many of them are just openai under the hood, this shouldn't take too long.