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

The annotations already establish this as a read-only, idempotent, closed-world operation, so the bar is lower, and the definition adds genuinely new behavior: the tools execute in the user's browser, the user must be handed the link, and files never reach the server or the assistant. That execution-location detail is exactly the kind of context annotations cannot express. Rate limits or failure modes for an unknown slug are not covered.

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?

Two sentences, scope front-loaded in the first clause, no filler. The middle clause listing all returned fields is dense but earns its place given there is no output schema.

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 definition must describe return values, and it names the four field groups returned. It also covers the key operational constraint, execution in the browser, and that files stay local. What is missing is minor: behavior on an unknown or ambiguous slug.

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 both parameters are fully documented in the schema, including the enum and the localized-slug/URL fallback. The description only adds that the slug originates from find_tools or list_tools and that URLs exist in every language, which is marginal over the schema. 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 definition states a specific verb and resource, "Details of one tool by its slug", and immediately identifies the fields it returns: name, description, page URL per language, and in-page WebMCP agent tools. Referencing find_tools and list_tools as the source of the slug cleanly separates it from those siblings.

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 tells the agent where the slug comes from, namely find_tools or list_tools, and instructs "give the user the link" because the tools run in the user's browser. The description implies the single-item lookup role but never explicitly states when to prefer it over list_tools or find_tools.

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