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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: images/carousels return null views and engagementRatePct with metricAvailability=false while likes/comments/shares/saves remain available, and captions are truncated to 300 chars. This is real value, though no total-count or paging-envelope behavior is described.

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?

Lead sentence front-loads the resource and return shape, followed by tightly packed clauses on edge-case metrics, filters, sorting, paging and truncation. It is dense but every sentence earns its place; the fragment style is efficient rather than padded.

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?

There is no output schema, so the description must convey returns, and it reasonably does: metrics, classificationSources, classification sub-fields (funnelStage, format, communicationStyle, mediaType), null-metric behavior, and caption truncation. Paging envelope and total counts are the only notable omissions for an 11-parameter list tool.

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 carries the burden and largely does: it documents ISO format for since/until, the mediaType enum values, sortBy options with default ordering, and limit default 20 / max 100 with offset for paging. Only brandId is left unexplained, which is a minor gap given the otherwise strong compensation.

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 ('List the brand's published posts with metrics, classificationSources and classification') and even clarifies the surprising scope that images/carousels are included despite the 'videos' name. However, it never distinguishes itself from closely named siblings like list_contents, list_carousel_posts, or list_creator_videos, so the agent must infer which list tool applies.

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 filters (platform, since/until, funnelStage, format, minViews, mediaType) and sortBy options imply when the tool is useful, giving implicit usage context. But there is no explicit when-to-use versus alternatives guidance and no named sibling to route to, so routing remains inferred rather than stated.

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