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

Annotations already carry readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered; the description adds substantial context beyond that — the ENTITLEMENT_DENIED gate on free plans before any read, the PIT data sourcing (SEC filings with accepted_at ≤ as_of_date, nearest prior trading day), the zero look-ahead bias guarantee, and the TTM computation method. No contradiction with the annotations.

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 purpose and the omit-date behavior, then organized into thematic blocks (usage, sourcing, returns, plan gating, alternatives). It is long (~380 words for a 2-param tool) and the enumerated return list overlaps the existing output schema, so it could be trimmed — but every sentence carries real decision-relevant information and nothing is 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?

For a 2-param tool with an output schema and rich annotations, this is near-total: entitlements and upgrade envelope, provenance contract, data lineage, TTM methodology, and alternatives are all covered. The one genuine gap is the unresolved conflict between 'Omit as_of_date' and the schema's required field, which leaves an agent unable to reconcile the two sources of truth.

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 baseline is 3, and the description does add meaning (CIK accepted as ticker, nearest-prior-trading-day resolution, plan-dependent history window). However, it actively misleads: 'Omit as_of_date and it returns today's...' directly contradicts the schema's required array, which lists as_of_date as required. An agent following the description would send a call that fails validation — the description fights the structured contract instead of reinforcing it.

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 resource and scope ('Current and historical valuation multiples for a company') and explicitly differentiates from siblings by name — get_financial_ratios and get_valuation_metrics are offered as the alternatives for fiscal-year-end multiples. An agent can tell exactly what this returns (P/E, P/S, P/B, EV/EBITDA, EV/Revenue, FCF yield) and how it differs from nearby valuation tools.

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?

Gives explicit when-to-use ('any "what is X's P/E" / "how is X valued right now" question'), an explicit when-not ('never derive a multiple yourself — that is exactly the arithmetic the provenance contract forbids'), and named alternatives for free-plan users. It also lists concrete use cases (historical screens, backtesting entry-point multiples, forensic audits), leaving nothing to inference.

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