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

Annotations already declare the operation read-only, idempotent, closed-world, and non-destructive. The description adds useful behavioral context by identifying the data source ('from the latest trustee report') and listing the certificate attributes returned, though it does not describe not-found behavior.

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 a single, front-loaded sentence with no redundant wording. It presents the lookup key, resource type, and returned fields efficiently.

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 simple one-parameter lookup with no output schema, the description gives enough context about the data source and returned fields for an agent to call it correctly. It falls short only on edge-case behavior such as missing or invalid CUSIPs.

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 single parameter is fully documented in the input schema. The description adds only that the CUSIP identifies a CMBS certificate class, which is modest value beyond the schema.

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 states a specific verb and resource: 'Look up a CMBS certificate class by CUSIP.' It also enumerates the key fields returned, making the tool's scope clear against siblings such as get_trust and search_loans.

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 implies when to use the tool: when you have a CUSIP and need certificate-level CMBS data from the latest trustee report. It does not explicitly name alternatives or state when not to use it, leaving routing between siblings largely to inference.

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