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

Annotations already declare readOnly, idempotent, and closed-world behavior. The description adds substantial context beyond that: exact return fields, unsupported-script error behavior, and pricing/payment details over x402.

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?

Front-loaded with the core action and standards, followed by return values, error behavior, and pricing. Every sentence adds information without redundancy.

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?

Given a 4-parameter tool with rich schema coverage, annotations, and no output schema, the description covers purpose, supported standards, return contents, error behavior, and payment. Nothing essential is missing for correct invocation.

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%, so the schema already documents all parameters. The description adds useful semantic distinction between the standards, including ISO 9's one-to-one diacritic behavior and BGN/PCGN's Russian-system scope.

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 (transliterate), source and target scripts (Cyrillic to Latin), and the named standards (ISO 9:1995, BGN/PCGN). An agent can immediately distinguish this from text_slug, text_similarity, and text_unicode.

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?

Provides clear context: Cyrillic only, with explicit rejection of other scripts via UNSUPPORTED_VALUE. It also explains the two standard choices, but does not explicitly route the agent away from or toward sibling text tools.

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