plan_add

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

Annotations already declare readOnlyHint=false and destructiveHint=false, consistent with the mutation described. The description adds value by explaining insertion positions ('at the end or immediately after the current active step'), offering behavioral detail beyond 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?

Two sentences deliver purpose, usage context, and positional behavior without redundancy. Every phrase earns its place, and the structure is front-loaded with the core action.

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?

With simple 3-parameter schema, helpful annotations, and clear usage context, the description is nearly complete. It doesn't mention return values or side effects, but for a low-complexity mutation tool with strong schema support, this is a minor gap rather than a critical omission.

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%, so baseline is 3. The description adds meaning beyond the schema by clarifying the 'after_current' position means 'immediately after the current active step', which is not fully explicit in the schema's enum description.

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 action: 'Add steps to an existing plan' with the specific resource (plan) and target (steps). It also distinguishes from siblings by noting mid-plan usage and positioning options, which differentiates it from plan_set and plan_advance.

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?

Provides a clear usage context: 'Use when new work is discovered mid-plan.' It implies a specific scenario but does not explicitly name alternatives or say when not to use, though the sibling list and context make the distinction intuitive.

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