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

Annotations already carry the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), lowering the bar. The description adds context beyond annotations by declaring the tool standalone (no workflow dependencies) and noting the input is validated upstream. No contradiction with annotations.

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 is front-loaded with the core purpose, then uses clearly labeled sections (WORKFLOW, INPUT CONTRACT, DO NOT CONFUSE WITH) that each earn their place. Slightly long but efficiently organized with zero filler; the docs link consolidates the full contract rather than inlining it.

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 values need not be spelled out. The description covers the input contract, workflow dependencies, sibling disambiguation, and points to a docs URL for the full output/error contract. For a read-only two-parameter tool this is nearly complete, with only the error behavior deferred to the external docs.

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% — both date (YYYY-MM-DD format) and response_format (markdown/json enum with default) are documented in the schema. The description's INPUT CONTRACT note ('date string only') reinforces but does not add semantic detail beyond what the schema already provides, so the baseline 3 applies.

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 states a specific verb (derives), resource (Lo Shu three-by-three frequency grid), input source (birth-date digits), and the analytical outputs (planes, missing/repeated digits, per-digit traits). It also explicitly names two sibling tools it should not be confused with, which sets it apart from the dozens of numerological siblings.

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 'DO NOT CONFUSE WITH' section explicitly routes the agent to asterwise_get_numerology_profile for letter-based Western numbers and asterwise_get_name_correction for spelling harmonics. The INPUT CONTRACT states the sole accepted input (date string) and that validation is handled upstream, giving clear when-to-use and when-not-to-use guidance.

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