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

Annotations already cover readOnly, non-destructive and closed-world, so the description's real contribution is the credit-cost disclosure ('does not consume credits'), which annotations cannot express and which matters for agent decision-making. It does not describe response shape or freshness of the tariff data, but for a static metadata read that is a minor gap.

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?

A single front-loaded sentence listing the returned capability categories, followed by one short exclusion clause. No filler, and the most decision-relevant fact (no credit cost) lands early.

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 parameters, no output schema and read-only annotations, the description carries the full burden of saying what comes back, and it does so by naming the capability categories. An agent knows exactly what this call yields and that it is free.

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 to disambiguate; baseline 4 applies. The description's mention of an 'input contract' is a hint about downstream call shapes but does not need to document any argument here.

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 (Read) and enumerates the exact resource set: supported sources, coverage, account availability, credit tariffs, input contract and caveats. The closing clause ('Does not run research or consume credits') separates it cleanly from the search/pipeline siblings that do run research.

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 negative clause 'Does not run research or consume credits' implicitly routes agents here for discovery/pre-flight rather than execution, which distinguishes it from search_leads and run_pipeline_sample. It stops short of an explicit 'call this before running research' instruction or naming a sibling directly.

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