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

Annotations already cover readOnly, idempotent, non-destructive and closed-world. The description adds genuinely new operational facts beyond them: the call is 'Free, no key' — no authentication needed and no credit consumed by the estimate itself. It does not describe the response shape or whether estimates are per-call or aggregate.

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 telegraphic clauses, zero filler, with the core purpose front-loaded and the default and auth facts trailing. Every phrase 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?

For a one-parameter read-only tool this is nearly sufficient, but with no output schema the description never indicates what comes back (per-tool costs, totals, units beyond 'credit'). A brief return-value hint would close the remaining gap.

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 optional `tools` array, and the description only partially compensates: it clarifies the empty/omitted case means 'all tools'. It does not state whether entries are exact tool names as listed in the sibling set, or how unknown names are treated.

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?

Names the resource precisely (credit cost of TRYIT tools) and the scope default (all tools if none given), which no sibling covers — siblings like account_status or keyword_trend are content operations. It lacks an explicit verb ('Estimate...'), reading as a noun phrase, but the intent is unambiguous.

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?

'before calling them' clearly signals the pre-flight use case: check cost prior to invoking a paid tool. The 'all tools if none given' clause documents the no-argument behavior. No explicit exclusions or named alternatives, but none are needed since no sibling overlaps.

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