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

Annotations already declare readOnlyHint and openWorldHint, so the description need not repeat those. It adds valuable context: the text is untrusted content (data, not instructions) and the tool never opens paid posts even when entitled. This goes beyond annotations and helps an agent handle content safely. No contradiction with 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 verbose and heavily metaphorical ('ciphertext', 'Seal session', 'agent library'), which obscures the straightforward action. The first sentence is clear, but the following security explanation is lengthy and could be condensed. It is not appropriately concise for a simple read operation.

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?

Given the tool's simplicity (one parameter, output schema present), the description covers the essential behavior: reads public text, is read-only, and has specific security caveats. The parameter is fully documented in the schema, so the description doesn't need to explain return values. The main flaw is clarity, not missing information.

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 input schema has 100% description coverage for the single parameter postId, including the caveat that it is not a URL or title. The tool description adds no extra parameter semantics beyond the schema, so the baseline of 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 clearly states the verb 'read' and the resource 'public text of a post', which is specific and understandable. It also differentiates from siblings by emphasizing it only reads and never spends, though the metaphorical language adds unnecessary complexity. It could be more direct but the core purpose is evident.

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 gives clear context: it reads public text only, and warns that paid or subscriber posts are not opened by this tool, even if purchased. This tells the agent when to use it (for public posts) and what it cannot do. However, it doesn't explicitly name alternatives for paid content, so it stops short of full routing guidance.

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