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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds meaningful context beyond that: cursor-based pagination behavior, an access requirement for content, and a person-only restriction. It still doesn't say what happens if access is missing, but it meaningfully supplements the annotations.

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 with the core behavior front-loaded, followed by access and audience constraints. No filler or repetition.

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?

The tool has an output schema, so return values need not be explained, and annotations cover safety. The description adds pagination, access, and person-only context, but the undocumented limit parameter keeps it from being fully complete.

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 must carry parameter meaning. It explains the cursor parameter and implies conversation_id via 'one conversation's messages,' but it says nothing about the limit parameter's default, maximum, or behavior, leaving a significant gap.

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 states a specific verb and resource: 'Read the latest page of one conversation's messages,' which clearly distinguishes reading a single conversation from listing many. It doesn't explicitly name the sibling conversation_list as an alternative, but the contrast between 'one conversation' and a list is implicit.

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 explains how to page: use no cursor for the latest page, or a cursor for older pages. It also states a prerequisite ('Current access to every retained private source is required') and a scope restriction ('Person only'), but does not explicitly say when to use this versus conversation_list or dm_read.

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