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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered structurally. The description still adds non-obvious operational context: it spends no credits and takes no arguments, which matters for a metered speech service and is not derivable from the annotations. It doesn't discuss rate limits or staleness, but the gaps are minor.

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 the returned fields, then usage triggers, then behavioral guarantees. Every sentence carries distinct information with no repetition of the title or name.

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?

Although an output schema exists (so return values need not be re-explained), enumerating the fields is cheap and helps the agent decide whether to call it for a given user question. Combined with clear triggers, siblings, and the free/read-only guarantee, the definition is sufficient to call correctly with no follow-up questions.

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?

The tool takes zero parameters, so there is no parameter semantics to explain; the closing 'Takes no arguments.' is a useful confirmation rather than filler. Baseline of 4 for a zero-param tool is warranted.

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 ('Check') and resource ('the signed-in user's Audexum account') and enumerates exactly what is returned: plan, credits_left, usage_percent, period_resets, V4 availability, pricing link. It also implicitly separates itself from audexum_guide by scoping this tool to the live account rather than plan/cost reference material.

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 three concrete trigger conditions (before a long generate_speech/transcribe job, when the user asks about remaining credits, after an insufficient-credits error) and routes the agent elsewhere for adjacent needs ('For what plans include or cost, use audexum_guide; to upgrade, give the user pricing_url'). This is explicit when-to-use plus named alternatives.

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