Send Message to Jules Session

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already indicate this is a write operation (readOnlyHint=false) and not idempotent or destructive. The description adds valuable context beyond annotations: it requires an active session, describes the return value ('Confirmation that the message was sent'), and gives concrete examples of appropriate messages. This helps the agent understand behavioral expectations without contradicting the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise and well-structured: a one-line summary, a short 'Use this to' clarification, a simple Args list, a Returns line, and examples. Every section earns its place without unnecessary verbosity. The front-loaded purpose statement makes it easy for an agent to quickly identify the tool's function.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is simple (two string parameters, no output schema), and the description covers purpose, parameters, return value, and examples, making it sufficient for invocation. It does not detail error conditions, but the annotations and schema cover the core safety and type constraints. Given the low complexity, this level of completeness is appropriate.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, with both sessionId and prompt already described in the schema. The description repeats the parameter descriptions but adds value through concrete examples ('Please also add integration tests', 'Use TypeScript instead of JavaScript') that illustrate the kind of content to include in the prompt. These examples enhance understanding beyond the schema's simple field descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description starts with a clear and specific verb-resource pair: 'Send a message to an active Jules session.' It clearly distinguishes this tool from siblings (create/get/delete/list sessions, approve plan) by focusing on the action of sending a message while a session is active. The elaboration about feedback, questions, and instructions further clarifies its specific role.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use the tool: 'Use this to provide feedback, answer questions, or give additional instructions while Jules is working on a task.' This provides clear context and purpose, though it does not name alternative tools or explicitly state when not to use it. The sibling list implicitly offers alternatives, but that is outside the description itself.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.