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

The annotations already establish read-only, idempotent, and non-destructive behavior. The description adds useful context beyond those annotations by revealing that the output is a coverage map with first-available dates and that the only parameter is the row cap. No contradiction with annotations is present.

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?

The description is two sentences with zero filler. The core concept is front-loaded, followed by actionable usage guidance and a brief parameter note. Every sentence earns its place.

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 simple zero-required-parameter listing tool, the description covers purpose, return content, use cases, and the single optional parameter. The explicit statement of what the tool returns compensates for the absence of an output schema, and the annotations cover safety semantics.

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 input schema already documents max_rows thoroughly, including the default, cap semantics, and guidance to prefer filters over raising the cap, so the schema carries the parameter meaning. The description only confirms that there are no other parameters, which is helpful but does not add substantial meaning beyond the schema.

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 clearly defines the tool as a coverage map listing every available ticker with its first available date, which is a specific resource and deliverable. It distinguishes itself from sibling data tools by framing its role relative to get_historical_market_cap, so an agent can tell it apart without opening the schema.

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?

It explicitly says when to use the tool: check whether a name is covered before querying get_historical_market_cap, or enumerate the full point-in-time universe. It names the alternative tool directly and provides a clear decision rule, 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.