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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: "Needs no account" (auth requirement), "a version never changes" (immutability), and the newest-by-default resolution rule, plus the note that Spaicely fetches files so code need not be retyped.

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-loaded with what the tool returns, then the workflow, then the parameter behavior. Every sentence carries information, though the deploy/snippet workflow instruction is somewhat tangential to a read tool and lengthens 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?

There is no output schema, so the description must describe returns — it does, listing files, the HTML snippet, and usage notes, and it gives the shape of the deploy_files entries. Minor gaps remain (structure of the notes or file list), but an agent can call this 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. The description still contributes meaning beyond the schema by stating that omitted version yields the newest and that a pinned version is immutable — the latter is not in the schema and affects whether an agent should pin.

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?

"Gives one building block from blocks.list" names a specific verb and resource and explicitly anchors it to the sibling tool that enumerates blocks. The follow-on sentence enumerates the payload (files, HTML snippet, notes), so an agent knows exactly what it gets back versus calling blocks.list.

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 clearly routes the agent: get names from blocks.list, then use the result with sites.deploy via deploy_files. That is concrete downstream usage context, though there is no explicit "when not to use" or edge-case exclusion beyond the version default note.

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