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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is fully covered. The description adds the per-request cost context, which is genuinely useful, but says nothing about return format, caching, or the cik-vs-ticker preference — acceptable given the rich annotations.

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 single-sentence description is front-loaded and free of waste, and the pricing note is a clearly delimited injected block. Sizing is appropriate, though the minimal content borders on under-specification rather than tightness.

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?

An output schema exists, so return values need no explanation, and annotations carry the safety profile. However, for a two-optional-parameter lookup tool whose scope ('company facts') is undefined, the description leaves the caller without enough to choose between cik and ticker or to know what will be returned conceptually.

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 100%, so both params are already documented; baseline 3 applies. The description's 'for a ticker' hints at ticker usage but does not clarify the more important ambiguity that both cik and ticker are optional (required: []), leaving the agent unsure which identifier to supply.

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 verb and resource ('Get company facts') but 'facts' is generic and undefined, and it makes no attempt to distinguish itself from close siblings like get_financial_financials, get_financial_filings, or get_financial_financial_metrics. An agent cannot tell from the text what data class 'facts' covers versus those 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?

Only 'for a ticker' is offered; there is no when-to-use guidance, no prerequisite, and no mention of alternatives among the many financial siblings. The agent must infer selection criteria entirely on its own.

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