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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavioral detail: it returns aggregate submitted/accepted par amounts, switches to per-security detail when cusips is supplied, and clarifies the difference between seclending and extensions.

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 dense sentences deliver the resource, scope, date flexibility, operation types, return behavior, and example queries with no filler. The most important query intent is front-loaded before the parameter-dependent details.

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 read-only tool with no output schema, the description explains what is returned (total par submitted/accepted, per-security detail when cusips is provided) and what questions it answers. It stops slightly short of specifying exact response fields or default date behavior, but the schema and examples cover most operational gaps.

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 schema already documents all five parameters. The description adds useful cross-parameter nuance—such as cusips triggering per-security detail—but does not need to compensate for missing schema information.

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 description clearly states the resource (NY Fed Desk securities lending) and the central query: how much of the SOMA portfolio was lent out today or over a date range. It distinguishes itself from sibling Fed tools by focusing specifically on securities lending operations rather than repo, holdings, or dealer stats.

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?

The description gives explicit example use cases: 'how active is securities lending today' and 'was CUSIP X lent out this week'. It provides clear context for when to use the tool, though it does not explicitly name sibling tools to avoid or state when not to use it.

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