enter_plan_mode

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

With no annotations, the description properly discloses that the tool 'is non-destructive; it only marks state so the workflow is observable.' It does not mention any side effects, but it is sufficiently transparent for the agent to understand the safe, stateful nature of the tool.

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, with a clear purpose statement, usage guidelines, a workflow bullet list, and a parameter section. Every sentence adds value without redundancy.

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?

Given the tool's low complexity and the presence of an output schema (which presumably describes the response), the description covers purpose, usage, and parameters adequately. It does not elaborate on the output, but the schema is expected to handle that.

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 description coverage is 0%, but the description adds meaning for both parameters: 'reason' is a short note on why plan mode is warranted, and 'goal' is a one-line description of the plan's achievement. This compensates for the missing schema 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 clearly states the tool's function: 'Enter plan mode before attempting any complex, multi-step, or file-modifying task.' It specifies the verb (enter) and resource (plan mode), and distinguishes it from siblings like exit_plan_mode and todo_write.

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 provides explicit when-to-use guidance: 'Use this PROACTIVELY for non-trivial coding, refactoring, or destructive operations.' It also details the subsequent workflow: research, todo_write, exit_plan_mode, and wait for approval, while advising against write/edit/exec during planning.

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