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

Annotations already declare readOnlyHint, idempotentHint, and closed-world behavior, but they say nothing about auth. The description adds the non-obvious fact that no authentication is required, which is genuinely useful for an agent deciding whether it can call before sign-up. It does not discuss caching, response shape, or freshness beyond 'exact current pricing'.

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?

Front-loads the most decision-relevant fact ('No authentication required'), then one dense enumerative sentence, then the usage cue. Efficient, though the middle sentence is a long comma list that is informative rather than elegant.

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?

With no output schema available, the description carries the burden of telling the agent what comes back, and it does so item by item (credits, packs, subscription, per-operation costs, refunds, rate limits, license). Combined with the auth note, an agent has everything needed to call and interpret this tool.

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 nothing for the description to disambiguate and the baseline is 4. The description correctly implies a parameterless, snapshot-style fetch rather than a parameterized query.

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?

Specific verb+resource ('get_pricing') with an explicit enumeration of what the payload covers: starter credits, credit packs, subscription, per-operation credit costs (sprite generation, background removal, upscale, Spine), refunds, rate limits, licensing. This is clearly distinguishable from siblings like get_service_info, list_actions, and list_models, which cover capabilities/actions/models rather than cost.

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 a concrete use case: 'Use this to estimate the cost of a task before asking the user to sign up,' which tells the agent when in a workflow to call it. It stops short of naming sibling alternatives or exclusion conditions, so it is clear context without full routing guidance.

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