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

This goes well beyond the annotations: it discloses that the tool is 'PROPOSED, never performed directly', returns status='confirmation_required' with an action_id and plan_token, and requires confirm_action to complete. That is exactly the behavioral context an agent needs for a non-read-only tool, and it is consistent with destructiveHint=false and an 'additive and low-risk' characterization.

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 text is front-loaded with purpose, then requirements, then a clearly labeled CONFIRMATION block. Every sentence carries actionable information, and the deliberate sectioning makes the confirmation step hard to miss.

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?

For a three-parameter mutation tool with no output schema, the definition covers the call, the ownership constraint, the default, and the full confirm-then-write lifecycle. Nothing an agent needs to invoke it correctly is missing.

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?

With 0% schema description coverage, the description does real work: it identifies goal_id's ownership constraint and position's default-to-end behavior. It does not explain the integer-or-string duality of goal_id, leaving one gap that the raw schema flags but does not clarify.

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?

States a specific verb and resource ('Add a checkable milestone') plus the scope constraint ('one of the caller's goals'), which is enough for an agent to act. It does not explicitly contrast itself with sibling tools like update_milestone or complete_milestone, relying on the verb 'Add' to carry that distinction.

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 definition gives clear preconditions ('goal_id must be the caller's own goal') and explains the confirmation-based invocation path, ending with when the actual write occurs. It provides strong context for how to use it, though it never states when to prefer a different tool or what to do if the goal is not the caller's.

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