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

Annotations already declare readOnlyHint and idempotentHint, but the description still adds real behavior: ordering is driven by first_chars, output is cut off at max_names, and input characters must be registered and non-disabled or duplicated. The duplicate rule is slightly ambiguous (within a pool vs across the two positions), which keeps this from a 5.

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?

Two compact sentences with the generation rule front-loaded, followed by constraints and sibling routing. Every clause carries information; nothing is repeated from the title or schema verbatim.

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?

An output schema exists, so return-value description is unnecessary. For a pure, read-only generator the description covers the source constraint, generation rule, ordering, truncation, and the downstream tools an agent needs, leaving nothing essential unstated.

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 each parameter is already documented; the description goes beyond that by explaining the interaction between first_chars and second_chars (omitting the latter means single names) and by tying max_names to generation order and truncation rather than a bare cap.

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 (compose) and resource (candidate names) and precisely defines output semantics: single name = one char from first_chars, double name = first_chars x second_chars, ordered by first_chars and truncated at max_names. It also names the sibling tools for adjacent steps, so it is distinguishable from naming_pick/naming_check/naming_character 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?

Explicitly routes usage: the character pool must come from naming_pick, evaluation of the produced candidates goes to naming_check, and single-character facts go to naming_character. It also states a precondition (only already-collected, non-disabled characters) and a rejection rule for duplicates.

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