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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the safety profile is covered. The description adds genuinely non-redundant behavior: unindexed numbers fall back to a pattern classification plus reduced single digit. The cost note is vague ('see your plan') and adds little.

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 front-loaded sentences with no wasted prose; the fallback behavior comes second where it belongs. The bracketed cost line is a placeholder that neither helps selection nor informs invocation.

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 described, and annotations cover the safety profile. Purpose plus the fallback rule fully equip the agent to invoke this three-parameter, single-required lookup correctly.

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?

With schema description coverage at 100%, the schema fully documents `number`, `fields`, and `precision`, so the baseline is 3. The description only restates that the input is a specific sequence and echoes the fallback already stated in the `number` schema description, adding no new syntax or format detail.

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 and resource ('look up the meaning of a specific angel number sequence'), which makes the number-oriented lookup distinguishable from numberless siblings in principle. However, it never names the confusingly similar siblings (astroway_esoteric_angel_numbers, _decode, _by_life_path_n) to make the distinction explicit.

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?

Usage is only implied by the fact that it consumes a 'specific angel number sequence,' and the fallback sentence tells the agent unindexed numbers are still handled. There is no explicit routing guidance toward alternative angel-number tools like _decode or _today, so the agent must infer the choice.

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