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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, and the description adds value beyond them: no authentication is used, so private content is inaccessible, and each value carries a source page, read timestamp, and rounded flag, with withheld metrics surfaced in not_public. This is substantive behavioral disclosure, not a restatement of the annotations.

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?

Three sentences, front-loaded with the core action and metrics before the constraint and limitation. Dense with information and free of filler, though the enumeration of return fields borders on more detail than a caller needs.

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 one-parameter read tool with annotations and an output schema, the description covers the operation, the platform scope, the authentication boundary, and the shape of returned values, so an agent has everything needed to call it correctly and interpret results.

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% for the single url parameter, so baseline is 3, but the description adds meaning by specifying the accepted address types (YouTube video/Short, TikTok video, X post), which sharpens what the agent should pass.

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?

Names a specific verb and resource ('Read the public numbers of one post') and enumerates exactly which metrics are returned (views, likes, comments, shares, saves, post time) across three named platforms. This clearly separates it from compare_posts (multi-post comparison) and list_channel_stats (channel-level).

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?

Gives a clear scope boundary: it only works on public posts and explicitly states private posts and account analytics are out of reach because it never signs in. That is a useful when-not condition, though it does not name compare_posts as the alternative for multi-post comparison.

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