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

Annotations already declare readOnly/idempotent/non-destructive, so the description rightly spends its words elsewhere: it discloses that media URLs are presigned and can be pulled into context to actually view the creative, and that the tool has a two-phase retrieve-then-show contract keyed on resultId. Those are non-obvious behaviors an agent could not infer from structured fields.

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 sentences, both load-bearing. The return payload is front-loaded and the follow-up show workflow comes second, matching the order in which an agent needs the information.

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?

No output schema exists, and the description does a good job enumerating the returned fields, so return-value clarity is covered. The one gap is the required adId and the workspace/project scoping rules, which are handled only inside the schema property descriptions.

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 67% and the description never mentions adId, projectId, or workspaceId. The required adId has no description anywhere in the schema, so the description could have compensated and does not. With two of three params documented in-schema, this sits at the baseline rather than below it.

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 (fetch) and resource (one ad) and enumerates the payload: copy, creative caption, duplication facts, landing page, and presigned media URLs. The singular 'one ad' plus the media-URL detail clearly distinguishes it from sibling sightglass_find_ads, which searches rather than retrieves.

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?

Gives explicit post-call guidance: results are data-only, nothing is rendered until sightglass_show is called once with the returned resultId, and the show call does not re-search. That routing context is strong. It stops short of an explicit 'use this instead of sightglass_find_ads when you already have an adId' statement.

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