Read any post in full

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), yet the description adds three pieces of genuinely new context: the return format (markdown), the fact that paywalled content is included, and an explicit prompt-injection warning telling the agent to treat the text as data, not instructions. That last point is rare and highly valuable for an open-world content-reading tool.

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 short sentences with zero filler: what it returns first, then the access scope, then the safety instruction. The scope and the injection warning are front-loaded rather than buried, and every sentence carries distinct information.

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?

With no output schema, the description correctly compensates by naming the return format (markdown) and the content class (other people's text). It stops short of covering failure modes such as an inaccessible or non-existent post, but for a 2-parameter read tool with full annotation coverage the essentials are present.

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% – both post_id (numeric id from list_reader_posts or a feed) and publication (loose hostname match, defaults to first connected publication) are fully documented in the schema. The description adds no syntax, format, or defaulting detail beyond that, so the baseline 3 applies.

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?

States a clear verb+resource ('Read the full text of any post') and adds an authorisation scope ('you have access to, including paid posts from publications you pay for') that separates it from public-scraping or own-post tools in the sibling list. It does not explicitly name which sibling to prefer (get_post, scrape_post, list_reader_posts), so an agent must infer the routing from the access-scope wording.

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 establishes the precondition for use (a post you have access to, including paid ones), which implies usage context, but never states when NOT to use it or which sibling to pick instead when a post is your own, public, or a draft. The routing hint to list_reader_posts lives in the schema, not the description, so guidance here is only implied.

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