Read a published post

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, so the description does not need to restate those. The description adds valuable behavioral context beyond annotations: this tool can read any public Substack and returns the full post body, not just metadata.

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 with no filler. The core action is front-loaded, and the cross-publication capability is presented as a meaningful addition without redundancy.

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 simple read operation with rich annotations and a fully documented schema, the description is complete. It communicates the essential behavior, scope, and a distinguishing use case, and nothing critical is missing for an agent to invoke the tool 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?

Schema description coverage is 100%, so the input schema already documents all four parameters well, including slug format, body_format enum/default, and publication selection semantics. The description itself does not add parameter meaning, but the baseline of 3 is appropriate because the schema carries the full burden.

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 opens with a specific verb and resource ('Read a published post in full by its slug') and clearly scopes the operation. It differentiates from sibling tools like get_draft and get_post_by_id by specifying slug-based access to published posts.

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 provides clear usage context: it works on any public Substack, not just the user's own, and explicitly calls out the competitor-reading use case. It does not explicitly enumerate when to prefer get_post_by_id or other read alternatives, but the slug-based and public-scope guidance is strong enough for an agent to select it appropriately.

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