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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile is covered; the description adds real substance with no output schema present by specifying the payload: balance and distress, named parties, every certificate class with CUSIP/coupon/losses/credit support, and liquidated loans with severity. It stops short of behavior on edge cases, such as what happens when a name fragment matches multiple trusts or when nothing matches.

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?

A single dense sentence, front-loaded with the resource and the lookup key, followed by the payload inventory in a logical order. The trailing list is long but every item earns its place by telling the agent what fields come back; only the missing leading verb costs it a point.

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 one required string parameter fully documented and no output schema, the description's main job is to convey what a call returns, and it does so thoroughly — parties, certificate classes, losses, credit support, liquidated loans. Combined with annotations that carry the read-only safety profile, an agent has everything needed to decide to call it and interpret the result.

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% and the single parameter already documents both slug ('benchmark-2018-b8') and fragment ('BANK 2019-BNK16') forms with examples, so the description's 'by slug or name fragment' is largely redundant. The enumerated return contents are valuable but they describe output, not the parameter, so baseline 3 applies.

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 names the resource ('A trust (deal)'), the lookup key ('by slug or name fragment'), and enumerates the record's contents, which lets an agent distinguish it from get_loan or get_loan_parties. What it lacks is an explicit verb — it reads as a noun phrase describing returned data rather than 'Retrieves a single CMBS trust' — and it never names list_trusts as the browse alternative.

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?

There is no when-to-use or when-not-to-use guidance and no mention of siblings such as list_trusts (browse all trusts) or get_loan (loan-level detail). The only usage-adjacent information is the accepted key format, which is already covered by the schema, leaving the agent to infer routing from the tool name alone.

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