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

Annotations already establish this as a safe read (readOnlyHint=true) against a closed system (openWorldHint=false), so the description only needs supplemental context. It adds real value: newest-first ordering, that all send sources are covered, and which outcomes are reported (status, opened, clicked, replied). Pagination mechanics (cursor/limit behavior) are only hinted at with 'Page through'.

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 tight sentences, front-loaded with the core operation and followed by the filtering options. No redundant restatement of the name or title.

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 an 8-parameter paginated list tool with no output schema, the description covers what is returned, ordering, scope, and filtering well enough to call it correctly. The remaining gap is pagination detail — cursor semantics and the 50/200 limit bounds are left entirely to the schema.

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 only 25%, so the description has to compensate, and it does: it names email, contact, campaign, broadcast and status as the narrowing dimensions and reveals the mutual-exclusivity constraint that the schema does not express. limit and cursor remain unelaborated beyond 'Page through'.

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 and resource ('Page through every email a project sent'), plus scope details that disambiguate it from a single-send lookup: newest-first ordering and 'from every source'. It does not explicitly name a sibling (e.g. get_send or list_email_events) as the alternative, so it falls just short of full differentiation.

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?

'Narrow by one of: an address, a contact, a campaign, a broadcast, or status failed' gives concrete guidance on how to scope the query and implies the filters are mutually exclusive rather than combinable. It stops short of when-not-to-use guidance or routing to a sibling tool for other needs.

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