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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds genuinely new behavioral facts: null means 'Soclo does not have this figure' and never 0, and this read never implies a post caused a sale or revenue. Those are data-semantics guarantees an agent cannot derive from the schema or annotations, and they prevent a serious misreading of missing metrics.

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?

Front-loaded with purpose and metric list, then the important null semantics, which is good ordering. The final sentence is somewhat redundant, restating the non-causal point twice ('that is a different, explicitly non-causal read' and 'is never claimed here'), which costs a little tightness.

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 metric enumeration and overview description usefully stand in for return-value documentation, and the null caveat is essential. Remaining gaps are minor: no mention of date-range defaults, grouping of per-post vs per-account results, or result size/pagination for a 4-parameter read.

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 source, toDate, fromDate and accountId are already documented in the schema (including the pointer to soclo_accounts_list for accountId). The description adds no parameter-level meaning, no date-format or default guidance, so the baseline 3 applies.

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 ('Read') and resource ('per-post and per-account performance') and enumerates the exact metrics returned (impressions, reach, likes, comments, shares, saves, views, clicks, engagement rate) plus the overview block. It also explicitly carves itself out from soclo_sales, so an agent can route between the two without opening a schema.

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?

Names the alternative explicitly ('that is a different, explicitly non-causal read (soclo_sales)') for the revenue/causality question, which is real routing guidance. However it gives no guidance on date-range defaults, on how it relates to soclo_analytics_follower_stats, or on when it should not be used, so it stops short of full when/when-not coverage.

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