tools: delete ToolDef and FunctionDef

ToolDef and FunctionDef are gone. Tool definitions are static strings
on the Tool struct. The API layer builds JSON from Tool::to_json().

- ChatRequest.tools is now Option<serde_json::Value>
- start_stream takes &[Tool] instead of Option<&[ToolDef]>
- openai::stream_events takes &serde_json::Value for tools
- memory_and_journal_tools() returns Vec<Tool> for subconscious agents
- Subconscious agents filter by t.name instead of t.function.name

No more runtime JSON construction for tool definitions.
No more ToolDef::new(). No more FunctionDef.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/agent/api/mod.rs

@@ -17,7 +17,7 @@ use std::time::{Duration, Instant};
 
 use tokio::sync::mpsc;
 
-use crate::agent::tools::{ToolCall, ToolDef, FunctionCall};
+use crate::agent::tools::{self as agent_tools, ToolCall, FunctionCall};
 use crate::user::ui_channel::{UiMessage, UiSender};
 
 /// A JoinHandle that aborts its task when dropped.
@@ -41,6 +41,12 @@ pub struct SamplingParams {
 //  Stream events — yielded by backends, consumed by the runner
 // ─────────────────────────────────────────────────────────────
 
+/// Build the tools JSON string from a slice of Tools.
+fn tools_to_json_str(tools: &[agent_tools::Tool]) -> String {
+    let inner: Vec<String> = tools.iter().map(|t| t.to_json()).collect();
+    format!("[{}]", inner.join(","))
+}
+
 /// Events produced by the streaming API backends.
 /// The runner reads these and decides what to display where.
 pub enum StreamEvent {
@@ -98,7 +104,7 @@ impl ApiClient {
     pub fn start_stream(
         &self,
         messages: &[Message],
-        tools: Option<&[ToolDef]>,
+        tools: &[agent_tools::Tool],
         ui_tx: &UiSender,
         reasoning_effort: &str,
         sampling: SamplingParams,
@@ -109,7 +115,8 @@ impl ApiClient {
         let api_key = self.api_key.clone();
         let model = self.model.clone();
         let messages = messages.to_vec();
-        let tools = tools.map(|t| t.to_vec());
+        let tools_json = tools_to_json_str(tools);
+        let tools_value: serde_json::Value = serde_json::from_str(&tools_json).unwrap_or_default();
         let ui_tx = ui_tx.clone();
         let reasoning_effort = reasoning_effort.to_string();
         let base_url = self.base_url.clone();
@@ -117,7 +124,7 @@ impl ApiClient {
         let handle = tokio::spawn(async move {
             let result = openai::stream_events(
                 &client, &base_url, &api_key, &model,
-                &messages, tools.as_deref(), &tx, &ui_tx,
+                &messages, &tools_value, &tx, &ui_tx,
                 &reasoning_effort, sampling, priority,
             ).await;
             if let Err(e) = result {
@@ -131,7 +138,7 @@ impl ApiClient {
     pub async fn chat_completion_stream_temp(
         &self,
         messages: &[Message],
-        tools: Option<&[ToolDef]>,
+        tools: &[agent_tools::Tool],
         ui_tx: &UiSender,
         reasoning_effort: &str,
         sampling: SamplingParams,

src/agent/api/openai.rs

@@ -8,7 +8,6 @@ use anyhow::Result;
 use reqwest::Client;
 use tokio::sync::mpsc;
 
-use crate::agent::tools::ToolDef;
 use super::types::*;
 use crate::user::ui_channel::{UiMessage, UiSender};
 use super::StreamEvent;
@@ -22,18 +21,19 @@ pub(super) async fn stream_events(
     api_key: &str,
     model: &str,
     messages: &[Message],
-    tools: Option<&[ToolDef]>,
+    tools_json: &serde_json::Value,
     tx: &mpsc::UnboundedSender<StreamEvent>,
     ui_tx: &UiSender,
     reasoning_effort: &str,
     sampling: super::SamplingParams,
     priority: Option<i32>,
 ) -> Result<()> {
+    let has_tools = tools_json.as_array().map_or(false, |a| !a.is_empty());
     let request = ChatRequest {
         model: model.to_string(),
         messages: messages.to_vec(),
-        tool_choice: tools.map(|_| "auto".to_string()),
-        tools: tools.map(|t| t.to_vec()),
+        tool_choice: if has_tools { Some("auto".to_string()) } else { None },
+        tools: if has_tools { Some(tools_json.clone()) } else { None },
         max_tokens: Some(16384),
         temperature: Some(sampling.temperature),
         top_p: Some(sampling.top_p),

src/agent/api/types.rs

@@ -9,7 +9,7 @@
 use chrono::Utc;
 use serde::{Deserialize, Serialize};
 
-use crate::agent::tools::{ToolCall, ToolCallDelta, ToolDef};
+use crate::agent::tools::{ToolCall, ToolCallDelta};
 
 /// Message content — either plain text or an array of content parts
 /// (for multimodal messages with images). Serializes as a JSON string
@@ -87,7 +87,7 @@ pub struct ChatRequest {
     pub model: String,
     pub messages: Vec<Message>,
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub tools: Option<Vec<ToolDef>>,
+    pub tools: Option<serde_json::Value>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub tool_choice: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]

src/agent/mod.rs

@@ -306,10 +306,9 @@ impl Agent {
                     top_p: me.top_p,
                     top_k: me.top_k,
                 };
-                let tool_defs: Vec<_> = me.tools.iter().map(|t| t.to_tool_def()).collect();
                 me.client.start_stream(
                     &api_messages,
-                    Some(&tool_defs),
+                    &me.tools,
                     ui_tx,
                     &me.reasoning_effort,
                     sampling,

src/agent/tools/mod.rs

@@ -18,7 +18,7 @@ mod write;
 // Agent-specific tools
 mod control;
 mod vision;
-pub mod working_stack;
+mod working_stack;
 
 use serde::{Serialize, Deserialize};
 use std::future::Future;
@@ -55,19 +55,6 @@ impl Tool {
             self.parameters_json,
         )
     }
-
-    /// Build a ToolDef (for backward compat where ToolDef is still used).
-    pub fn to_tool_def(&self) -> ToolDef {
-        ToolDef {
-            tool_type: "function".to_string(),
-            function: FunctionDef {
-                name: self.name.to_string(),
-                description: self.description.to_string(),
-                parameters: serde_json::from_str(self.parameters_json)
-                    .expect("invalid JSON in tool parameters"),
-            },
-        }
-    }
 }
 
 /// Function call within a tool call — name + JSON arguments.
@@ -77,15 +64,6 @@ pub struct FunctionCall {
     pub arguments: String,
 }
 
-/// Function definition for tool schema.
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct FunctionDef {
-    pub name: String,
-    pub description: String,
-    pub parameters: serde_json::Value,
-}
-
-
 /// Partial function call within a streaming delta.
 #[derive(Debug, Deserialize)]
 pub struct FunctionCallDelta {
@@ -93,27 +71,6 @@ pub struct FunctionCallDelta {
     pub arguments: Option<String>,
 }
 
-/// Tool definition sent to the model.
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ToolDef {
-    #[serde(rename = "type")]
-    pub tool_type: String,
-    pub function: FunctionDef,
-}
-
-impl ToolDef {
-    pub fn new(name: &str, description: &str, parameters: serde_json::Value) -> Self {
-        Self {
-            tool_type: "function".to_string(),
-            function: FunctionDef {
-                name: name.to_string(),
-                description: description.to_string(),
-                parameters,
-            },
-        }
-    }
-}
-
 /// A tool call requested by the model.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ToolCall {
@@ -135,7 +92,6 @@ pub struct ToolCallDelta {
     pub function: Option<FunctionCallDelta>,
 }
 
-
 /// A tool call in flight — metadata for TUI + JoinHandle for
 /// result collection and cancellation.
 pub struct ActiveToolCall {
@@ -220,17 +176,11 @@ pub fn tools() -> Vec<Tool> {
     all
 }
 
-/// Return all tool definitions for the API.
-pub fn definitions() -> Vec<ToolDef> {
-    tools().into_iter().map(|t| t.to_tool_def()).collect()
-}
-
-/// Return memory + journal tool definitions only.
-pub fn memory_and_journal_definitions() -> Vec<ToolDef> {
-    memory::memory_tools().into_iter()
-        .chain(memory::journal_tools())
-        .map(|t| t.to_tool_def())
-        .collect()
+/// Memory + journal tools only — for subconscious agents.
+pub fn memory_and_journal_tools() -> Vec<Tool> {
+    let mut all = memory::memory_tools().to_vec();
+    all.extend(memory::journal_tools());
+    all
 }
 
 /// Create a short summary of tool args for the tools pane header.

src/subconscious/api.rs

@@ -46,13 +46,12 @@ pub async fn call_api_with_tools(
     let (ui_tx, mut ui_rx) = crate::user::ui_channel::channel();
 
     // All available native tools for subconscious agents
-    let all_tools = agent_tools::memory_and_journal_definitions();
-    // If agent header specifies a tools whitelist, filter to only those
-    let tool_defs: Vec<_> = if tools.is_empty() {
+    let all_tools = agent_tools::memory_and_journal_tools();
+    let agent_tool_list: Vec<_> = if tools.is_empty() {
         all_tools
     } else {
         all_tools.into_iter()
-            .filter(|t| tools.iter().any(|w| w == &t.function.name))
+            .filter(|t| tools.iter().any(|w| *w == t.name))
             .collect()
     };
     // Provenance tracks which agent:phase is making writes.
@@ -83,7 +82,7 @@ pub async fn call_api_with_tools(
             };
             match client.chat_completion_stream_temp(
                 &messages,
-                Some(&tool_defs),
+                &agent_tool_list,
                 &ui_tx,
                 &reasoning,
                 sampling,

src/subconscious/knowledge.rs

@@ -295,13 +295,13 @@ fn run_one_agent_inner(
     _llm_tag: &str,
     log: &(dyn Fn(&str) + Sync),
 ) -> Result<AgentResult, String> {
-    let all_tools = crate::agent::tools::memory_and_journal_definitions();
+    let all_tools = crate::agent::tools::memory_and_journal_tools();
     let effective_tools: Vec<String> = if def.tools.is_empty() {
-        all_tools.iter().map(|t| t.function.name.clone()).collect()
+        all_tools.iter().map(|t| t.name.to_string()).collect()
     } else {
         all_tools.iter()
-            .filter(|t| def.tools.iter().any(|w| w == &t.function.name))
-            .map(|t| t.function.name.clone())
+            .filter(|t| def.tools.iter().any(|w| w == &t.name))
+            .map(|t| t.name.to_string())
             .collect()
     };
     let tools_desc = effective_tools.join(", ");