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

Beyond readOnlyHint/openWorldHint, the description discloses the five-result cap, the zero-cost behavior, the rejected URL input, an upcoming auth change date, and the privacy_consent_required failure mode with an explicit warning not to fabricate acceptance. That is substantial context an agent could not infer from annotations.

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?

The core purpose is front-loaded, but the middle sentences drift into a future key-requirement date and privacy-version policy that are verbose relative to the tool's simplicity. Several clauses could be tightened 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?

For a two-parameter read-only lookup with no output schema, the description covers result limits, auth expectations, cost, and the consent failure path. The main gap is that it never describes the shape of the returned word list, which an agent might want given the absence of an output schema.

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 0%, so the description must carry the burden, and it partly does: 'rhymes or meaning-related words' maps directly onto the rhyme/means enum, and the word parameter is implied by 'find words' for a given term. It omits the 40-character limit and does not define the enum values explicitly, keeping it below a 5.

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 first sentence names a specific verb ('Find'), resource ('rhymes or meaning-related words'), upstream source (Datamuse), and result cap (five). That distinguishes it from siblings like hub_dictionary, though it never explicitly says how it differs from that closest neighbor.

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?

It gives concrete conditions: supply word and relation, note that no key is needed now, that no points are spent, and that a URL is not accepted. The privacy_consent_required caveat tells the agent what happens on failure. It stops short of naming when to prefer hub_dictionary instead.

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