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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered structurally. The description adds only the 'single record' scoping, saying nothing about missing-record behavior or error shape — useful but thin on top of the annotations.

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 sentence with zero filler; the identifier options are front-loaded and readable at a glance.

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 two-parameter read tool with full annotation coverage, no output schema, and no nesting, this is close to sufficient: the operation and its lookup keys are unambiguous. The only real omission is the both-null / both-provided edge case, which matters because no parameter is required.

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 parameter meaning, and it partially does by presenting advertisement_id and advertisement_uuid as alternative lookup keys. It does not explain the expected UUID format, mutual exclusivity, or that both are optional at the schema level — gaps left entirely to the schema's 'anyOf null' typing.

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?

States a specific verb and resource ('Fetch a single advertisement') and names the two lookup keys, so the agent can distinguish it from list_advertisements, create_advertisement, and the get_advertisement_* sub-resource siblings. It stops short of an explicit contrast statement, but 'single' does the differentiating work.

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?

No guidance on when to use this versus list_advertisements or the other get_advertisement_* tools. Nothing says what to do when neither identifier is supplied, or which identifier takes precedence if both are given — a real ambiguity given that both parameters are nullable with default null.

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