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

Annotations already establish the read-only, non-destructive, non-open-world safety profile, so the bar is lower. The description adds genuinely useful context beyond that: the call is free/not metered, the HTML payload is a large raw blob that is sanitized, and the plain-text body is preferable for reading.

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 the resource being fetched, then the return content, then the billing note. Dense but every clause carries information; the em-dash-heavy phrasing is slightly harder to scan but not wasteful.

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 description correctly describes what comes back (plain-text body, optional htmlBody) and covers all three parameters. The only shortfall is that it never addresses how this differs from get_store_email_html, leaving sibling selection partly ambiguous.

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 real semantic value for includeHtml — what it returns (htmlBody), when to enable it (visual re-rendering/artifact), and the size/tradeoff warning — plus it reinforces emailId's provenance.

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 names a specific retrieval action on a specific resource ('One captured marketing email, by store domain and email id') and identifies the sibling that produces the id (get_store_emails). An agent can distinguish this single-item fetch from the list-producing sibling 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 clearly states the precondition (the id comes from get_store_emails) and gives a when-to-use rule for includeHtml ('only set when re-rendering the email visually'). It does not, however, acknowledge the closely related sibling get_store_email_html, which an agent might otherwise consider an alternative — the one obvious routing gap.

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