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 real value by disclosing the response contents (short definition, more detail, report location, measurement method, related terms, page) – important since there is no output schema. It omits failure behavior when a term is unknown.

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 front-loaded sentence with no filler; the long parenthetical example list is useful but pushes the payload-heavy content toward the end. Minor trimming of six examples would tighten it without losing meaning.

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?

With one simple read-only parameter and no output schema, the description does the essential job of describing return values. It leaves open what happens for an unknown or misspelled term and when to prefer search_glossary, which matters given the sibling set.

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?

There is one parameter at 100% schema coverage, and the schema already explains that it accepts a term, abbreviation, or alternate name. The description's example terms ('crown angle', 'feather', 'fluorescence') add some concrete guidance on the vocabulary accepted, but no format or matching rules.

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 names a specific resource (a single gemology term) and enumerates concretely what a definition contains, so an agent knows exactly what comes back. It never states the verb/scope relative to siblings (list_glossary, search_glossary), so it does not differentiate itself from them explicitly.

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: the description repeatedly says 'one gemology term', which suggests exact single-term lookup rather than listing or searching. It never names search_glossary as the alternative for fuzzy or partial matches, and gives no exclusions or preconditions.

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