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

Annotations cover the safety profile (readOnly, idempotent, openWorld, non-destructive), and the description adds genuinely novel behavior: it is a cache lookup, misses yield a single approximate reconstruction ('a guess, not attested'), and coverage grows so an identical query may later return a dictionary hit. That volatility disclosure is exactly the kind of context structured fields cannot carry.

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-loads the core purpose, then layers in lookup semantics and the reconstruction caveat in logically ordered sentences. Dense but every sentence carries weight; minor tightening possible around the source=reconstruction explanation.

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 no explanation, yet the description still clarifies the source=dictionary vs source=reconstruction distinction and the approximate=true flag. For a one-parameter lookup with rich annotations, nothing an agent needs is missing.

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 a single parameter and 100% schema description coverage, the schema already documents format, length bounds, and the source/approximate return semantics. The description reinforces the inverse-direction framing but adds no syntax or format detail beyond what the schema provides, so the baseline 3 is appropriate.

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 ('Find the real Livonian word(s) whose pronunciation-romanization matches this clean-ASCII input') and explicitly frames itself as the inverse of `livonian_romanize`, which cleanly distinguishes it from that sibling.

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?

Gives clear context for when to reach for it (the reverse direction of romanize, resolving romanized input back to orthography). It does not, however, compare against the other siblings like `livonian_search`, so the routing guidance is good but not complete.

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