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

Annotations already declare readOnly, idempotent, non-destructive and a closed-world dataset, so the description's job is lighter. It adds real value by disclosing the result shape (ticker, name, sector, company page) and the coverage constraint (US-listed, EquiReason-covered companies), which is not in the structured fields.

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 sentences, zero filler, scope stated before return values. Nothing redundant.

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 output schema, the description usefully summarizes return fields, and coverage limits are stated. The only omission is any mention of the limit/result-count behavior, which matters for a search tool.

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 coverage is 50%: query is documented in the schema, and 'by ticker or name' merely echoes it. The limit parameter (1-25) is never mentioned in the description, so the description does not compensate for the coverage gap.

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?

Specific verb and resource with scope qualifiers: 'Find US-listed companies covered by EquiReason by ticker or name.' It also names the returned fields, so the agent knows what it gets. Naming the sibling get_company and contrasting single-fetch vs. search would earn a 5.

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 'by ticker or name' phrasing implies the lookup case, but there is no explicit statement of when to use this versus get_company (e.g., search first, then fetch details). Usage is inferable but not guided.

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