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

Annotations already establish read-only, idempotent, closed-world behavior, yet the description adds substantial non-obvious context: no API key required, latest-filing-wins deduplication, derived:true tagging with the Q4 = FY minus Q1–Q3 derivation and its restatement caveat, a staleness flag, and inclusion of predecessor-company history after a ticker reorg. It also explains progressive coverage loading (~25 companies/day, priority tiers), which pre-empts misreading an empty result as an error.

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 definition is front-loaded with purpose, then the sibling routing, then behavior — a sensible order with no filler sentences. It is dense and long, particularly the parenthetical explaining Q4 derivation mechanics, which could be tightened, but each sentence carries distinct operational information rather than restating structured fields.

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?

There is no output schema, so the description must convey the return shape, and it does: per-period concepts, per-value provenance (form, filed date, accession number), derived markers, staleness flags, and predecessor-company periods. Combined with the coverage caveat and the zero-required-parameter behavior, nothing an agent needs to interpret results is missing.

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 cik, ticker, limit, and period are already documented, including the CIK-over-ticker precedence the description repeats. The description adds no additional parameter nuance such as limit semantics or period-selection trade-offs beyond what the schema states, so the 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?

The first sentence names a specific resource (standardized financial statements from SEC EDGAR XBRL filings) and enumerates the concept families returned (revenue, net income, EPS, cash flow, balance sheet) with ordering (latest periods first). It also explicitly separates itself from get_metric_history and list_financial_concepts, so an agent can route without opening a schema.

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?

It states the selecting condition directly: 'Use for period-by-period statements; use get_metric_history instead for one concept's long time series.' It also names list_financial_concepts as the discovery path for available concepts and warns that a valid company can legitimately return 'no financials stored yet,' which prevents false-negative retries.

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