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

Annotations already declare read-only, idempotent, non-destructive behavior, and the description adds valuable behavioral context beyond that: the node's ordering (shorter names first, then byte order), the pagination contract using next_after until exhausted is true, and the security-relevant warning that names and values are user-controlled.

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?

Three dense sentences with no filler: purpose, ordering, pagination, and trust considerations are each covered in sequence. Essential information is front-loaded before secondary details.

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 annotations covering safety and idempotency, an output schema available, and all params documented in the schema, the description supplies the remaining needed context: result ordering, pagination mechanics, and untrusted-data caveats. Nothing crucial for correct invocation or interpretation 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?

The input schema already documents all three parameters with 100% coverage, so the description does not need to repeat their meaning. It adds marginal semantic value by tying 'prefix' to the active-name enumeration behavior and by noting untrusted user input, but it does not meaningfully extend the schema's parameter documentation.

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?

Description uses a specific verb-resource pair ('List active names that start with a prefix') and specifies the ordering, making the tool's function unmistakable. It also distinguishes this from sibling tools like lookup_name by emphasizing prefix enumeration rather than exact lookup.

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 clearly implies when to use the tool: when you need to enumerate active names by prefix and page through results. It does not explicitly name alternatives or state when not to use it, but the prefix-list semantics and pagination instructions provide strong contextual guidance.

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