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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds the cost (10 credits, Tier 1) and the POST endpoint, which is genuinely useful behavioral context, but says nothing further about response behavior or limits.

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 definition is short and front-loads the core purpose in the first sentence, with the bracketed metadata kept compact. Every element earns its place, though the tag block adds some structural noise.

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 explained, and the tool is a simple idempotent read. However, the role of the required 'date' parameter and the lack of any guidance distinguishing this system's Expression number from the many sibling Expression tools leave it only minimally complete.

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 50%: 'fields' and 'precision' are documented in the schema, while 'name' and 'date' are not. The description clarifies 'name' as the full birth name, but never explains what 'date' represents (birth date vs. reference date) or its format, leaving a meaningful semantic gap.

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 (calculate Expression/Destiny number) and specifies both the letter basis (all letters, reduced) and the Chaldean system, which separates it from the vowel-based soul_urge or the pythagorean/kabbalistic/vedic expression siblings. It does not explicitly name an alternative, but the systematic sibling naming plus the 'all letters' and 'Chaldean' qualifiers make its identity inferable.

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?

There is no explicit when-to-use or when-not-to-use guidance and no routing to alternatives such as astroway_numerology_pythagorean_expression or the kabbalistic/vedic variants. The [Group: Numerology: Chaldean] tag implies the domain but gives no selection criteria, leaving usage entirely to inference.

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