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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive. The description adds two useful facts beyond them: the data source (Datamuse API) and a cost of 1 credit. It says nothing about result ordering, whether the source word is excluded, or how failures behave, so it is modest added value rather than rich disclosure.

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, front-loaded with what the tool returns. The 'Helps with vocabulary variety' sentence is slightly promotional filler but the credit-cost note earns its place. Nothing is buried or padded.

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 simple two-parameter lookup with full schema coverage and read-only annotations, the description covers the essentials. But with no output schema, it could say more about what a result entry looks like or how 'closely related' differs from a plain thesaurus, leaving the agent to discover the shape of the response.

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 both 'word' and 'limit' are documented in the schema, which sets the baseline at 3. The description adds nothing about the parameters (e.g. whether limit defaults to 20 or the 1-100 range), and notably does not flag that the schema types 'limit' as a string despite describing it as an integer.

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: 'Returns a list of synonyms and closely related words for a given term.' The scope ('closely related words') is clear. It loses a point because it never distinguishes itself from the closely related sibling words_meaning_like, which by name covers nearly identical ground.

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?

No when-to-use or when-not-to-use guidance at all. With siblings like words_meaning_like, words_sounding_like, words_that_rhyme, and word_definition in the same family, an agent has to guess which one answers 'find me a similar word'.

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