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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered, but the description adds substantive context by disclosing the guide's contents (IPA, respelling, stress marking, tips, common-mistake note, examples) and the coverage limitation that only words Speakeroo has a guide for will work. It stops short of noting auth, rate limits, or error behavior for uncovered words.

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?

Two sentences, front-loaded with purpose before the content enumeration. The second sentence is a fragment ('Links to the guide, where you can record yourself...') and the six-item contents list is dense, but every item is informative rather than filler.

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-value explanation is technically optional, and the description's added enumeration is a bonus rather than a necessity. For a one-parameter read-only lookup, the coverage caveat plus content preview is enough for an agent to call it correctly; only failure/not-found behavior is left unstated.

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 0% for the single 'word' parameter, so the description has to carry some of the burden; it does convey that the input is a single English word (an implicit language constraint not encoded in the schema). It adds nothing about format, length limits, or handling of multi-word phrases, so the compensation is only partial.

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 description states a specific verb and resource (fetch a pronunciation guide for an English word) and immediately enumerates what the guide contains, so an agent knows exactly what comes back. It is trivially distinguishable from every sibling, which are all speech-analysis/transcript tools, not word lookups.

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 phrase 'an English word Speakeroo has a guide for' implicitly states a precondition (coverage-limited lookup) and the closing line hints at a follow-on recording/check action. However, there is no explicit when-to-use versus when-not, and no named alternative for words outside the guide's coverage.

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