today_messages

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

With no annotations, the description carries the burden and does reveal meaningful behavior: it reads from the local cache and is scoped to today UTC. However, it omits details like message ordering, whether the limit caps the result set, cache staleness behavior, and the return format.

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?

A single, front-loaded sentence with no filler. Every phrase ('today UTC', 'local cache') adds distinct semantic value.

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 description is adequate for basic invocation given the simple optional parameters, but with no output schema and no annotations it leaves gaps around return shape, ordering, pagination, and how this relates to sync_messages or get_new_messages. More context would help an agent choose and call it confidently.

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 100%, so the parameters are already documented. The description adds little beyond 'all messages', which slightly conflicts with the limit parameter's behavior, but it does not need to compensate for missing schema info.

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 uses a specific verb ('Get'), a precise resource ('all messages from today (UTC)'), and a clear source ('local cache'). This distinguishes it from siblings like search_messages, read_messages, and get_new_messages without needing to open schemas.

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 description implies usage for cached messages from today but provides no explicit guidance on when to choose this tool over similar siblings such as get_new_messages, read_messages, or search_messages. No exclusions or alternative conditions are mentioned.

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