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

With no annotations provided, the description carries the full burden of behavioral disclosure and exceeds expectations. It reveals internal keying via the point-in-time name master, the archive lag, the default to latest available period when no year/date is supplied, and the reported currency/millions convention. These are non-obvious behaviors not inferable from the schema.

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 information-dense with no filler. It is front-loaded with the core purpose and use cases, followed by key behavioral details. While it is somewhat verbose (four sentences with multiple clauses), every sentence contributes meaning, so it remains effectively concise.

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?

Despite lacking an output schema and annotations, the description covers most operationally critical context: what data is returned, how ticker resolution works, date default behavior, and value conventions. It falls short only on clarifying 'stype' parameter values and the exact output grouping format, but for tool selection/invocation it is largely complete.

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 only 20% (only 'ticker' is described). The tool description adds semantic value for 'date' and 'year' by explaining that omitting them returns the LATEST available period, but it does not explain 'stype' (segment type?) or 'limit' beyond schema defaults. Since coverage is low, more compensation was needed, though the descriptions provided are genuinely useful.

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 states the tool's function: 'Business + geographic SEGMENT breakdown for one company' and details what it decomposes (fiscal period, line of business, geography, ASC-280 operating segment, US state) with accompanying metrics. It also provides concrete examples of when to use it ('revenue mix by region... which line of business carries the margin'), making the purpose unambiguous and distinct from sibling fundamentals tools.

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 description explicitly instructs when to invoke the tool: 'Call it to see WHERE a company earns...' and gives example use cases. However, it does not mention alternatives or exclusions relative to other tools (e.g., when NOT to use it), so it stops short of full usage-guideline coverage.

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