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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds behavior those annotations cannot convey: the 40,000-character body cap, the `truncated` flag and what to do when it is set (open the canonical URL), the `id`-over-`slug` precedence, and the exclusion of drafts and scheduled content. These are exactly the operational details an agent needs before relying on the result.

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?

Purpose, lookup keys and precedence come first, then return contents, then limits, then routing guidance — a well front-loaded structure with no filler. The first sentence is long and semicolon-heavy with parenthetical asides, which slightly taxes scanning, but no clause is wasted.

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?

There is no output schema, and the description compensates by enumerating the returned fields (title, description, body, type, language, tags, canonical URL, source, update date). Combined with the truncation behavior and eligibility exclusions, nothing material is missing for a four-parameter read tool.

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 coverage is 100%, so the baseline is 3, but the description adds a constraint the schema cannot express: at least one of `id` or `slug` must be provided even though neither is formally required. The precedence rule is repeated from the schema's `slug` description, so the gain is modest rather than substantial.

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 ('Return one public MasterAI Now item in full') and immediately names the two lookup keys. It explicitly distinguishes itself from the sibling search_content, so an agent can choose between them without opening either schema.

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?

It gives an explicit when-to-use ('after search_content to read a lesson before explaining it') and an explicit when-not-to-use with the named alternative ('do not use it to browse (use search_content)'). It also states a negative eligibility rule: drafts and scheduled Guides are never returned.

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