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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safe read-only profile is covered. The description adds meaningful behavioral context by naming the returned info (plan, balance, limits, reset time) and a diagnostic use case ('explain why enrichment did not run'). It stops short of describing auth requirements or caching, but that is reasonable for a simple read.

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 the resource list, then the usage context. Every sentence earns its place with no filler or redundancy.

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?

The description fully specifies what the tool returns and when to call it. An output schema exists, so return-value details are handled elsewhere. For a zero-parameter read tool, nothing an agent needs to invoke it correctly is missing.

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 no parameter documentation is needed. The description correctly omits parameter semantics; the baseline for zero-parameter tools is 4, as the description does not need to compensate for anything.

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 specifies the exact resource and scope: 'the user's Sensefold plan, AI-enrichment credit balance, limits, and reset time.' This is a precise verb+resource statement that an agent can match to plan/usage questions without ambiguity, and no sibling tool overlaps with quota retrieval.

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 gives explicit when-to-use conditions: 'Use when the user asks about their Sensefold plan or usage, or to explain why enrichment did not run.' This routes the agent to the tool for both informational and diagnostic queries, and no alternative tool exists for this purpose.

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