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

The description adds useful behavioral context beyond the annotations: it returns one value per fiscal period with the originating filing, sources from structured XBRL (not free text), and notes that no authentication is required. This complements the readOnlyHint/idempotentHint annotations without contradicting them.

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 three compact sentences, front-loading the core purpose before adding data-source and prerequisite details. Every sentence adds value, and there is no redundant filler.

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?

Given the annotations already declare safety properties and an output schema exists to describe return values, the description covers the essential usage context: what the tool returns, data source, prerequisite, and auth requirements. Nothing critical is missing for an agent to invoke it correctly.

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 the schema already documents all five parameters. The description's mention of concept examples and the CIK prerequisite mostly repeats schema information, adding little beyond what is already structured.

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 a specific verb ('Get') and resource ('historical time series for a single standardized XBRL financial concept'), with concrete examples and scope (as reported by a company across SEC filings). However, it does not differentiate itself from the very similarly named sibling finance.edgar.xbrl_concept, so an agent might struggle to choose between them.

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 provides clear context: it's for fetching concept-level time series from SEC XBRL data, and it explicitly states the prerequisite (requires a CIK from sec-edgar.company_lookup). It does not, however, mention alternatives or when not to use this tool, so it falls short of a 5.

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