Complete the key fields in a tools/list tool object and a tools/call request

MCP splits tool use into two steps: discovery and invocation. The discovery step is **`tools/list`**. The host asks a server, 'what can you do?' The server replies with an array of tool descriptors. Each descriptor has three key fields. `name` is the unique identifier, like `search_docs`. `description` is plain-English text that tells the model when this tool is useful. `inputSchema` is a JSON Schema object spelling out the arguments the tool expects. The invocation step is `tools/call`. Once the model picks a tool, the host sends a request with just two things: `name` (which tool to run) and `arguments` (the actual values, matching the schema). The server runs the tool and replies with a `content` array, the output blocks the model reads back. If the tool failed, the reply sets `isError` to true instead of throwing a protocol error, so the model can see the failure and react. List to learn what exists, call to actually do it.

MCP separates tool discovery from tool invocation, and the two methods have distinct shapes. **`tools/list`** returns an array of tool descriptors. Each one carries three fields. The `name` is a unique string identifier. The `description` is human-readable text the model uses to decide when to call the tool. The `inputSchema` is a JSON Schema object defining the accepted arguments. The host turns each descriptor into a function-calling entry for the model. `tools/call` is the invocation. The request payload is minimal: `name` to pick the tool and `arguments` to supply the values. Those argument values must validate against that tool's `inputSchema`. The response is a `content` array of typed blocks, usually text, but images or embedded resources are allowed too. One detail trips people up. Tool failures do not surface as JSON-RPC errors. Instead the result sets `isError` to true and puts the error text in the content. Protocol errors stay reserved for problems like an unknown tool. This split lets the model see a tool failure and recover.