Insights for one Facebook/Instagram post

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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: it explains that metrics with no value are reported as 'MISSING' and should not be read as zero, and it clarifies that impression-family metrics have been replaced by Meta's own identifiers. This helps the agent interpret results correctly.

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 is reasonably concise given the amount of metric detail it packs. It front-loads the primary purpose, then enumerates metrics by platform with a semicolon, and ends with the critical MISSING note. Every sentence adds value; no fluff. While slightly long, the structure is clear and 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 read-only tool with three parameters and no output schema, the description covers the essential context: what metrics are returned, the two platform variants, and the special behavior for missing values. It does not discuss pagination or rate limits, but those are likely not critical for a single-post call. The description provides enough for an agent to call the tool correctly.

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 100%, so the parameters (pageId, postId, target) are already fully documented in the schema. The description adds little beyond what the schema states—it reinforces the post-level scope and hints that target changes the metric set, but this is also present in the schema's description for target. Thus, it does not significantly enhance parameter understanding.

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 returns performance metrics for a single organic post, and enumerates exactly which metrics per platform (Facebook and Instagram). It distinguishes itself from sibling tools like meta_page_insights (page-level) and instagram_insights (account-level) by emphasizing 'single post' and 'organic', making its scope unambiguous.

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 concrete use case: 'find which organic posts earned their reach before turning one into a paid ad.' This gives clear context for when to use it. However, it does not explicitly name alternative tools (e.g., meta_page_insights) or state conditions when NOT to use it, leaving the exclusion to inference from the 'single post' phrasing.

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