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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds traits they cannot express: it is free, works without a key, changes nothing, and the credit balance is deliberately unavailable via the API (surfaced on the web instead). That last point is a genuinely useful boundary an agent would otherwise guess wrong about.

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?

Purpose is front-loaded in the first sentence, followed by usage guidance and return details. The third paragraph enumerates every returned field, which is somewhat long given an output schema exists, but it remains scannable and each sentence carries information.

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?

A zero-parameter diagnostic with a declared output schema is fully covered: the agent knows what it does, when to call it, that it is safe and key-free, and what limitations to expect regarding credit balance.

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?

Zero parameters, so the baseline is 4. There is nothing for the description to disambiguate, and it correctly avoids inventing inputs.

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 and resource: checks whether the configured MnogoReels API key works and reports server settings. It is unmistakably distinct from every sibling, all of which deal with clips, assets, packs, transcriptions or articles.

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 an explicit trigger: 'Use it first when other tools fail with an authentication error, or when the user asks which account or mode is active.' Both a diagnostic and an informational use case are named, leaving nothing to inference.

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