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

Annotations already declare this a safe read (readOnlyHint=true, destructiveHint=false) and closed-world, so the description is free to add higher-value behavior: default restated-vs-as-reported semantics, row granularity per period type (flows vs balances), use of the company's own fiscal calendar, and a warning when an alias ends before other structured facts, hinting at an XBRL tag change.

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?

Front-loaded with the core action and scope, and every sentence carries distinct information (source, granularity, restatement default, warning, exclusions, alternatives). It is a single dense block rather than scannable segments, which slightly hurts structure but not economy.

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?

For an 8-param read tool with no output schema, the description supplies what the schema cannot: the shape of the returned time series, row granularity, default restatement behavior, and the caveat around sparse/truncated series. Combined with full schema coverage and annotations, an agent has everything needed to call 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 coverage is 100%, so the schema already documents all 8 params and the baseline is 3. The description goes one step further by explaining the observable effect of asOriginallyReported ('latest restated value unless set') and how fiscalPeriod interacts with the filer's fiscal calendar, which is meaning the schema alone doesn't convey.

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?

Opens with a specific verb+resource ('Get a single financial concept ... over time for a company') and immediately names the data source (SEC Company Facts XBRL, or non-US issuer filings). It draws a boundary against sibling tools by naming GetFinancialStatement and CompareFinancialFact and by excluding dimensioned disclosures like customer concentration.

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?

Explicit routing: 'For a full statement use GetFinancialStatement; to compare peers use CompareFinancialFact,' plus a stated out-of-scope case ('Dimensioned disclosures such as customer concentration are outside this consolidated-series tool'). Both when-to-use and when-not-to-use are covered.

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