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

The description goes well beyond the annotations, which only say readOnlyHint=false, idempotentHint=true, destructiveHint=false. It discloses credit economics (first Pro fetch costs one Prompt Pack credit, repeat fetches free), the free/Pro/Lifetime access matrix, an error when credits are exhausted, fair-use rate limits with exact numbers shared with open_builder, the no-blocking-if-opened-today carve-out, a possible second text block for free-plan accounts, and unknown-slug errors. Nothing here contradicts the annotations: idempotency holds for repeat slugs, and readOnlyHint=false is consistent with a possible credit spend.

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 and scope are front-loaded before the policy detail, and the example request at the end is a useful anchor. It is a dense single block though; the credit, rate-limit and free-plan-note clauses could be split or trimmed, since a couple of them are restated from other parts of the definition.

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 two-parameter fetch tool with an output schema (so return shape needn't be re-explained), the definition covers everything an agent must know before calling: cost, access gating, rate limits, failure modes, and sibling routing. The one gap — what the upgrade note block looks like — is minor given it is described as a short informational aside.

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 baseline would be 3, but the description adds decision-relevant meaning the schema lacks: include_prompt=false costs nothing and changes nothing, while true triggers the access check and possible credit spend. It also restates the exact slug format expectation, which reinforces the schema's 'lowercase, hyphenated' guidance with a worked example.

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?

"Returns one AnimatedWebs template by slug" gives a specific verb and resource, then enumerates exactly what comes back (description, stack, tags, access level, tools, licence, URLs, views/saves/likes, prompt). It also distinguishes itself from the two obvious siblings by naming search_catalog as the discovery path and open_builder as the hand-off alternative.

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 states both usage moments explicitly: inspect a template already found with search_catalog, and, after the user chooses, fetch the prompt to build in the current project. It names the alternative tool and the condition that selects it (open_builder for Lovable, v0 or Bolt). No inference is required.

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