get_messages

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

Annotations already declare readOnlyHint and idempotentHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: descending order and a prompt-injection warning that all names/text are untrusted third-party content — a valuable disclosure an agent would otherwise not have.

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?

Three short sentences with the core behavior front-loaded and no filler. The middle sentence's 'Pass next as cursor' phrasing is slightly awkward relative to the schema's 'cursor'/'next value' wording, but the text is otherwise tight.

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 no explanation, and the safety warning covers a real operational risk. Missing only minor context such as access scope (which chats the caller may read) and any rate/pagination limits beyond the default page size.

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 all three parameters are already documented, setting the baseline at 3. The description adds cursor direction ('for older messages') but confusingly refers to the value as 'next' rather than the actual parameter name 'cursor', which risks a naming mismatch rather than adding clarity.

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 ('Returns the messages of one chat') plus the ordering ('newest first'), which is enough to distinguish it from siblings like get_chat or search_messages. It never names a sibling explicitly, so it stops short of a 5.

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?

The phrase 'of one chat' and the pagination note imply the read-one-conversation use case, but there is no explicit guidance on when to prefer this over search_messages or get_changes, nor any exclusions. Usage is inferable but not stated.

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