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

Annotations already declare the tool as read-only, idempotent, and non-destructive. The description adds substantive behavioral context by enumerating the categories of information returned (platform rules, limits, settings, defaults, capture requirements), which goes beyond the abstract 'Get Channel Schema' title and 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?

The description is two sentences, front-loaded with the action and resource, and every clause adds value. The first sentence states functionality, the second sentence provides usage guidance. There is no fluff or repetition.

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 is simple (one parameter), has a rich output schema, and annotations cover safety. The description fully covers the return content categories and the appropriate use case. There is no missing information that would prevent an agent from using it 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?

The single parameter 'platform' is fully documented in the input schema, including a list of allowed identifier values (x, linkedin, etc.). The description does not add any additional meaning or context about the parameter beyond what the schema already provides, so the schema carries the full burden. Baseline 3 is appropriate.

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 begins with a specific verb ('Returns') and clearly identifies the resource (platform rules, character and media limits, required settings, safe defaults, capture requirements) as well as the target ('supported Postly publishing channel'). This distinguishes it from sibling tools like create/delete/update/validate, which perform different actions.

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 explicitly states when to use the tool: 'Use it before creating or scheduling content when the channel requirements are not already known.' It provides clear context but does not mention when not to use it or name alternative tools (e.g., postly_validate_post), so it stops short of a 5.

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