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

The description goes well beyond the annotations by disclosing deduplication ('names not already shown'), non-destructiveness ('nothing is removed', consistent with destructiveHint=false), zero cost ('Free'), a rate limit ('capped at a few rounds per run'), a way to know the remaining rounds, and the return shape ('Returns the run with its new names'). This is rich behavioral context for an agent. No contradiction with annotations found.

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 core action is front-loaded in the first sentence, and every sentence contributes useful information (purpose/dedup, cost, cap, return). The cap sentence is slightly verbose ('so you never have to hit the cap to find out') and could be tightened, but overall the description is efficient and well-ordered.

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 tool with one parameter, no output schema, and annotations present, the description covers all essential aspects: purpose, dedup behavior, non-destructiveness, cost, rate-limit handling, and return value. There is no output schema, so the description's explanation of 'Returns the run with its new names' is critical and provided. Nothing an agent needs to call 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?

Schema description coverage is 100% — the single `id` parameter is already documented as 'The brand-name run ID to extend', which fully conveys its meaning. The description's phrase 'existing brand-name run' reinforces this but adds no new syntax or format details, so the baseline 3 for high schema coverage is appropriate.

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 uses a specific verb ('append') and resource ('an existing brand-name run'), and clarifies the scope ('a fresh batch', 'names not already shown'). It clearly distinguishes itself from create_brand_names (which starts a new run) and get/list_brand_names (which read), so an agent can route correctly without opening sibling schemas.

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 phrase 'existing brand-name run' clearly signals this tool is for extending an already-created run, which implicitly excludes create_brand_names as the alternative for starting fresh. However, it does not explicitly name sibling alternatives or state 'use X when you need to start a new run', so the guidance is implied rather than explicit.

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