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

Annotations already establish read-only, idempotent, open-world behavior, so the safety profile is covered. The description adds meaningful context annotations cannot: stock-split-driven changes are excluded by default and the result carries cause attribution. That is real behavioral disclosure beyond the structured fields, though no pagination or rate-limit detail is offered.

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, no filler. The core definition and payload are front-loaded, and the trailing clause about omitting concept is a useful, compact instruction.

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 an output schema present, the description isn't obliged to explain return shape, and it still briefly characterizes the fields. Combined with full schema coverage and rich annotations, an agent has enough to invoke correctly; only cross-tool routing guidance is thin.

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 every one of the eight parameters is already documented (limit default/newest-first, since, offset via next_offset, concept default, periods enum, include_splits, min_change_pct). The description only restates the concept-default behavior rather than adding syntax or format meaning, so baseline 3 applies.

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 (List) and resource (periods whose value changed in a later filing), and enumerates the payload the agent gets back (first and latest values, % change, cause). This cleanly separates it from siblings like vintages or history, which concern as-filed data rather than restatements.

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 gives one usage hint -- 'Omit concept to scan everything' -- which tells the agent how to broaden the query. It never states when to prefer this tool over vintages, history, or known_as_of, nor any prerequisites. Usage is implied rather than spelled out.

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