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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful non-schema context — the 2-credit cost and the array-shaped result — but says nothing about coverage quality, missing-word behavior, or rate 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?

Three short sentences: purpose, input/return, cost. The cost note is front-loaded enough and nothing is padded. Minor waste in restating 'Thesaurus' twice at the start, but the text is otherwise tight.

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 one-parameter lookup tool with full annotation coverage, a 100%-documented schema, and an output schema, the description covers what the tool does, what it takes, what it returns, and its cost. Only the silence on ambiguous or unknown-word outcomes keeps it from full marks.

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 100% and there is a single required parameter whose schema description already explains it. The description's 'supply a single target word' reinforces the cardinality constraint but adds no format or semantics beyond the schema.

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 (finds) and resource (synonyms and alternative terms for any word), which lets an agent distinguish it from siblings such as AntonymFinder, WordOpposites, Dictionary, and RhymingWords without opening any schema.

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?

The description implies when to use it (looking up synonyms for a word) and constrains input to 'a single target word', but it never explicitly routes the agent away from near-neighbors like Dictionary or AntonymFinder, nor does it state exclusions.

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