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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds two useful facts beyond that — result ordering and a 1-credit cost — but says nothing about pagination limits, approximate result volume, or whether private profiles return errors.

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 front-loaded clause states the resource, ordering, and cost with no filler. The phrasing 'Photos a Facebook Page ... has posted' is slightly awkward as a sentence but remains efficient.

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 simple two-parameter read with no output schema, the description covers the essentials including ordering and cost. It is thin on what the returned photo objects contain and on cursor pagination behavior, which would help an agent plan multi-page retrieval.

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%, so both 'url' and 'cursor' are already documented in the schema, and the description adds no format or syntax detail beyond it. Baseline 3 applies since the schema carries the parameter burden.

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 (photos posted by a Facebook Page or profile) and the ordering ('largest size first'), which lets an agent distinguish it from facebook_profile_posts and facebook_profile_videos. It lacks an explicit verb, so it is clear rather than exemplary.

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?

Usage is implied by the phrasing 'Photos a Facebook Page or profile has posted' — an agent can infer this is the tool for image content from a profile. There is no explicit when-to-use versus when-not guidance and no naming of alternatives such as facebook_profile_posts or facebook_profile_videos.

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