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

With no annotations, the description carries the full burden, and it does disclose the payload in unusual depth: every stone for the month, colors, hardness, sources, story, baby meaning, keepsake ideas, a safety note, zodiac signs, quick answers, and a guide link. What it omits are operational traits such as auth requirements, failure modes for invalid dates, and whether the guide is static or computed.

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?

A single long sentence, but it is front-loaded with the core purpose before enumerating the contents, and every listed item corresponds to something the agent will receive. The enumeration is dense rather than padded; only the trailing directive sits awkwardly after the content list.

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 read-only, single-parameter tool with no output schema, the description is nearly self-sufficient: it enumerates the return payload and flags the one item that must be relayed to the user. Nothing critical is missing, though failure handling for a future date and the shape of 'quick answers' remain unspecified.

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 already 100% (pattern and 'not in the future' constraint are in the schema), so the baseline is 3. The description adds real meaning on top: the guide is keyed to the birth date's month, implying day and year do not change the result, which the schema alone does not convey.

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+resource ('Get the full birthstone guide') with the keying dimension ('for a birth date's month') made explicit, so the agent knows exactly what is produced. It does not explicitly distinguish itself from sibling get_zodiac_sign, even though the month's zodiac signs are part of its output, so sibling differentiation is only implied.

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 statement of when to choose this over get_zodiac_sign or the other baby-date tools, and no exclusions; usage is only inferable from the tool name and resource. The one directive given ('Always pass on the safety note with keepsake ideas') governs handling of the result rather than tool selection.

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