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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, which cover the safe read behavior. The description's 'Retrieve' aligns with these annotations but adds no extra behavioral context such as error handling or response format, so the bar is partially met.

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 description contains significant redundancy: the main sentence and the 'Guidance' sentence are nearly identical, and the trailing '| context: id' appears to be a template artifact. This bloats the text and distracts from the core message.

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 no output schema, the description does not need to explain return values. The parameter is well-covered and annotations handle safety. However, the ambiguous 'when needed' and lack of context about when to prefer this over list_photos leaves some gaps, though it is adequate for a simple get operation.

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?

The sole parameter 'id' is described as 'Photo item id returned by cms_list_photos', which gives clear provenance and meaning. This adds value beyond the schema's type and requirement, though it could be more explicit about the id being the specific photo identifier.

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 clearly states the tool retrieves a single CMS photo gallery item by photo id, using the specific verb 'Retrieve' and identifying the resource. It also mentions discovery via cms_list_photos, which helps differentiate it from list and other get tools, though the wording is slightly indirect.

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 provides a hint to use this after cms_list_photos discovery, but the guidance is vague ('when needed') and does not explicitly contrast with alternatives like list_photos or other get_* tools. There is a redundant 'Guidance' statement that adds little.

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