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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is covered. The description adds real value beyond that by disclosing the data provenance (SEC filings) and the exact metric set returned, which the agent cannot get elsewhere since there is no output schema.

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?

Two sentences, front-loaded with the identity and source of the dataset before the field enumeration. The long metric list is justified because no output schema exists, though it could be grouped slightly more tightly.

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?

With no output schema, the description correctly compensates by listing the returned fields (volume windows, loan sizes, median rate, leverage, property types, states, recent loans). The remaining gap is failure behavior for an unrecognized lender and the discovery path to a valid slug.

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% and the single parameter is already documented with examples, so the schema carries the burden. The description's examples ("Citi", "wells-fargo") reinforce that slugs are hyphenated lowercase, but add little beyond the schema's own examples.

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?

Names a specific verb and resource ("One CMBS originator's securitized book from SEC filings") and enumerates the returned metrics, so an agent knows exactly what it gets. It is distinguishable from find_cmbs_lenders by the singular "one lender" framing, though it never names that sibling to make the contrast explicit.

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?

"Give the lender's name or slug" implies the caller must already know a valid lender identifier, which hints that a lookup step may precede this call. But there is no explicit routing to find_cmbs_lenders for discovery, and no statement of what happens when the lender is unknown or ambiguous.

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