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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent write, so the safety profile is covered. The description adds a genuine behavioral constraint beyond the schema: target_amount must be > 0 and <= the goal target, which is the kind of validation detail the schema lacks.

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?

Front-loads the one-line purpose before the Args/Returns sections, and every line carries information. The docstring scaffolding (Args/Returns headers) adds minor verbosity but no wasted sentences.

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 non-idempotent mutation with no output schema, the definition covers purpose, all four parameters, the target_amount constraint, and confirms a created-milestone return. It omits side effects (e.g., whether reaching a milestone triggers the celebration notification) and error behavior, which are the remaining gaps.

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%, so the description carries the full parameter burden and largely does so: it explains goal_id as the parent goal, gives concrete name examples, constrains target_amount, and clarifies celebration_message is optional and shown on completion. It does not specify units/currency for target_amount, which is the only meaningful gap.

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 ('Create a milestone checkpoint within a goal'), which is distinctly more specific than the sibling list/create/update/delete_milestone names alone. It does not explicitly name sibling tools, so it stops short of a 5, but the scoping to a parent goal makes the purpose unambiguous.

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?

There is no explicit when-to-use or when-not-to-use guidance and no mention of alternatives such as update_milestone or create_goal_plan. The requirement for an existing parent goal is only implied by the goal_id argument, not stated as a prerequisite.

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