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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so safety profile is clear. The description adds the important behavioral context of being 'non-diagnostic', which complements the annotations without contradiction.

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 consists of two sentences with no wasted words. It front-loads the core purpose and filters, then provides a usage example and disclaimer. Every sentence earns its place.

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 simplicity, the existence of an output schema, and comprehensive annotations, the description is complete. It covers the source, filters, intended use, and a disclaimer, leaving no critical gaps for an agent to decide invocation.

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 100%, so the schema already documents all three parameters with descriptions. The description mentions 'optionally filtered by child age in months and developmental domain', which reinforces the schema but does not add new semantic meaning beyond it.

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 provides developmental milestones from a specific corpus, with optional filters for age and domain, and gives an example usage ('what should my child be doing at N months'). This distinguishes it from siblings like 'red_flags' or 'search', making its 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?

The description explicitly says to use it for 'what should my child be doing at N months' style questions, which provides clear guidance. However, it does not explicitly state when not to use it or suggest alternative tools, though the 'non-diagnostic' qualifier implies a limitation.

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