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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered without the description. The description does add the meaningful 'latest 40' cap and the per-value return fields (period, fiscal year, form, filing date, accession number), but says nothing about pagination beyond that cap, rate limits, or what happens if a concept is absent for the filer.

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?

A single front-loaded sentence with no filler, leading with what is returned and then the paging limit. It is dense enough that the list of return fields could be separated for readability, but nothing is wasted.

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 and no annotations carrying behavioral detail, the description takes on the burden and largely meets it by enumerating the per-value fields and the 40-record cap. It falls just short on edge cases such as a filer or concept with no reported values, which matters given openWorldHint.

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 100%, so all four parameters are already documented, including the default concept of Revenues and the us-gaap taxonomy default. The description adds only the framing that cik and ticker are alternative identifiers, which is a marginal gain over the schema; 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 and resource: reported values of one XBRL concept for one SEC filer from EDGAR filings. The scope (single concept, single filer, latest 40) is unambiguous and clearly distinct from the procurement/offer siblings, none of which touch XBRL financial data.

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?

Usage is only implied through the 'by CIK or ticker' phrasing, which tells the agent how to identify the filer but not when to prefer this tool or when another source is needed. No explicit exclusions, prerequisites, or alternative tools are named.

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