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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), so the description's job is to add context — and it does: it defines the week boundary in UTC, discloses that null means a week was not counted and never zero, and states the minimum sample (8+ weeks) before 'patterns' claims appear. The explicit caution against causal/ROI readings is non-obvious output behavior that an agent would otherwise misreport.

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 opening clause is front-loaded and effective, and little of the content is filler. However, the metric inventory is a single dense run-on list ('likes, comments, saves and shares, profile visits, new followers and reach where Instagram and Facebook share them...') that is hard to scan, followed immediately by three separate interpretive rules in one paragraph; a compact structure would carry the same information more legibly.

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 carry the return shape — and it does, enumerating per-week fields, the 4-week moving average, member notes, the one-sentence 'story', and the conditional 'patterns' block. For a zero-parameter, read-only reporting tool, nothing an agent needs in order to call and correctly interpret it is missing.

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?

There are zero parameters, so the baseline is 4. The description does add one useful semantic constraint beyond the empty schema — the time window (last 12 weeks plus the current week) and the UTC Monday-to-Sunday week definition — which tells the agent what date range the results implicitly cover.

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 states a specific resource and scope: post performance week by week, covering the last 12 weeks plus the current one, with Monday-to-Sunday UTC weeks defined explicitly. This is clearly distinguishable from a generic analytics call, but it never names a sibling tool or contrasts itself with postfjord_get_analytics, so differentiation is inferred from granularity rather than stated.

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 rather than prescribed: weekly trend reading, 4-week moving averages, and member notes for launch weeks. There is no explicit 'use this when' statement, no exclusions, and no routing to an alternative for non-weekly or per-post questions; the only hard rules given ('only when 8 or more weeks support it', 'never turn these into an ROI') govern interpretation of the output, not tool selection.

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