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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuine context beyond that: the response ordering (newest first), returned fields, the source SHA-256 for provenance, and the strong caveat that values are accounting figures rather than returns. It omits auth/rate-limit behavior, so not a 5.

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, but the tail is padded with stacked disclaimers ('not market prices, returns, an investment recommendation, or ALPHAC performance' and a separate return-validation sentence). The intended meaning survives, but several clauses could be trimmed without loss.

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?

An output schema exists, so return values needn't be enumerated, and the description still covers the conditional response shape, ordering, provenance hash, and scope limits. For a read-only, 4-param tool this is near-complete; only auth/rate-limit context is absent.

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 baseline is 3. The description adds real conditional semantics not in the schema: omitting 'concept' returns the list of available histories, while supplying it returns observations — behavior the schema names alone don'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?

States a specific verb and resource ('SEC-reported financial history for one company ... by cik or ticker') and bounds the domain clearly (accounting reference, not market prices/returns). It does not name a sibling tool directly, but it points at external products and the validation API, so an agent can still separate it from the validate_* family.

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 conditional usage ('without a concept, the histories available; with one, observations newest first') and explicit when-not routing ('For point-in-time values use canli-fundamentals-mcp', 'Validate a separately constructed return series with the validation API; accounting values are not returns'). Alternatives are named, but they are mostly outside the sibling set, so it stops short of a full routing rule.

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