Preview page

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior: it is the same render used by PDF export, and callouts, tables, math, mermaid and diagrams are resolved, plus what each format value returns. It stops short of noting render cost, latency, or output size for image/both, which is a minor gap.

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?

Front-loads the core purpose, then usage, then parameter semantics, then the sibling routing note — a sensible ordering with little waste. The dense em-dash clauses make it slightly heavier than necessary, but 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?

There is no output schema, so the description carries the return-value burden, and it does: text reads the page back as plain text, image returns a screenshot, both returns each. Combined with the routing note and render-behavior context, an agent has everything needed to call 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?

Schema coverage is 100%, so the baseline is 3, but the description goes beyond the schema by explaining the intent of each format value ('text ... enough to catch prose that the renderer swallowed or reordered'). It also confirms the default, which the schema states more tersely.

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 specific verb+resource ('render a page and read it back as the reader actually shows it') with the key differentiator that it uses the same render pipeline as PDF export. It explicitly names the sibling it is not for deck pages ('call preview_deck instead'), letting an agent disambiguate without opening any 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?

Gives concrete when-to-use conditions: verifying that written content renders as intended, and re-checking after any edit whose result can't be inferred from markdown alone. It also supplies the negative case (deck pages → preview_deck), so routing is fully determined.

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