list_emails

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

The readOnlyHint=true annotation already establishes the safety profile, so the bar is lower. The description does add real behavioral value beyond annotations: newest-first ordering and, importantly, the cursor contract ('Cursor from a previous page's next_cursor to continue listing'), which reveals pagination. It still says nothing about how multiple filters combine or result caps.

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?

The summary sentence is front-loaded before the Args block, and each argument line earns its place given zero schema coverage. The docstring-style enumeration is slightly formulaic but contains no filler.

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?

An output schema exists, so return values need not be described, and the readOnly annotation covers safety. The description adds ordering and pagination, the two things structured fields do not cover. Minor gaps: the default folder of INBOX and whether filters are AND-combined are not stated.

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 0%, so the description carries the full burden, and it does so: every one of the seven parameters gets a meaning, including match semantics ('From header contains this text'), the 1-100 bound on limit (absent from the schema), and the next_cursor round-trip for 'before'. This is substantially more than the schema names provide.

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 ('List the most recent messages of a folder') plus the sort order ('newest first'), which lets an agent distinguish it from a single-message reader like read_email. It does not, however, differentiate itself from search_emails, which is the closest sibling and the one an agent is most likely to confuse it with.

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?

Usage is only implied: the tool is for enumerating a folder's contents with optional narrowing filters. The one sibling reference ('as returned by list_folders') is a data dependency for the folder argument, not guidance on when to pick this tool over search_emails or get_thread, and no exclusions are stated.

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