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

Annotations already declare the write/open-world/idempotency profile, so the bar is lower. The description adds real scope context — only 'current public' records, exactly one record — and clarifies the canonical vs. original-source link distinction. It says nothing about behavior when an ID is unknown or stale, or about error/rate-limit behavior, so it is adequate rather than rich.

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?

Three sentences, front-loaded with the action and resource, then the precondition, then the field-level clarification. Dense but each sentence adds something; the field enumeration is slightly list-like but serves the return-value semantics.

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 need not be re-explained, yet the description still adds the canonical-vs-source URL semantics. Combined with the ID precondition and single-record guarantee, an agent has enough to call it correctly; only the failure path for unknown IDs is unaddressed.

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 0%, so the description must carry the parameter's meaning, and it does: the single id is a 'stable record ID' that must be 'exact' and already known. That tells the agent the input is a previously obtained identifier rather than a query string, though it gives no format or example value.

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 uses a specific verb ('Retrieve') and a specific resource ('one current public BrinkerAdvisor rate record'), and enumerates the returned dimensions (yield, term, freshness, canonical link, provenance). It doesn't name a sibling explicitly, but the 'when its exact stable record ID is already supplied' clause cleanly separates it from search, so an agent can distinguish it without opening the schema.

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?

It states the precondition for use ('when its exact stable record ID is already supplied', 'Requires one known ID') and the cardinality ('returns one record'), which implicitly tells the agent to use search first when no ID is known. No sibling is named as an alternative and there is no explicit exclusion, so it stops short of a 5.

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