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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds the meaningful behavioral detail that auto_spacing=true repairs mis-spaced input before splitting, but it says nothing about the return shape (tokens or offsets), which matters since no output schema exists.

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 short sentences, the splitting purpose is front-loaded, followed by the sibling routing and then the auto_spacing nuance. Nothing is redundant.

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 simple read-only tokenizer the purpose and alternative routing are complete, but with no output schema the description never indicates what is returned (token list vs. offset tuples), which the encoding parameter implies is relevant. That gap keeps it at minimum-viable-plus.

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 coverage is 100%, so the baseline is 3, but the description genuinely adds meaning: it explains that auto_spacing corrects incorrectly spaced sentences, beyond the schema's bare '자동 띄어쓰기를 적용한다'. The encoding parameter's effect on offsets is left to the schema.

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 ('한국어 문장을 어절(토큰) 단위로 분리') and immediately contrasts it with the POS-producing sibling analyze_syntax. An agent can pick it apart from the other syntax tools without opening any schema.

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?

Explicit when-to-use ('품사 정보 없이 어절 경계만 필요할 때') and names the concrete alternative for the opposite case ('형태소·품사가 필요하면 analyze_syntax'). No inference required.

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