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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows it is a safe read operation. The description adds behavioral detail by specifying what is returned: validation status, errors, warnings, platform readiness, and applicable limits. This goes beyond the annotations without contradicting them.

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?

Two sentences, front-loaded with the core action, no redundant phrasing. The first sentence states what it checks; the second states what it returns. Every word contributes value.

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?

The tool has a large schema and an output schema, which already carry detailed parameter and return information. The description captures the essential purpose and output scope. It doesn't mention prerequisites like workspace_id or the recommendation to call postly_get_channel_schema, but those are in the schema, so the description is adequate in context.

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 schema already documents every parameter. The description groups params into categories (text, media, platform settings, schedules, targets) which helps orient the agent, but it adds no new syntax or format details. Baseline 3 is appropriate given the high schema coverage.

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 uses a specific verb ('Checks') and clearly identifies the resource ('proposed post text, media, platform settings, schedules, and targets') and the validation target ('against Postly and platform-specific requirements'). It distinguishes from sibling tools like create_post or get_post_status by focusing on pre-publication validation and lists return types (validation status, errors, warnings, platform readiness, limits).

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 word 'proposed' implies the tool is for validating a draft before publishing, giving clear contextual use. However, it does not explicitly name alternatives (e.g., 'use before create_post') or state when not to use it, so it stops short of the highest score.

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