Read Google Chat messages

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds real value beyond that: field-by-field return shape, ordering, the 'You' author convention, and a latency warning tied to limit size. That is a solid contribution on top of annotations, though it does not discuss pagination mechanics or rate limits.

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?

Four sentences, each carrying distinct information: scope and ordering, return fields, thread pointers, and the limit/latency trade-off. Scope is front-loaded and no sentence is redundant with the schema or annotations.

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?

There is no output schema, and the description compensates by enumerating the returned fields and their formats, including the replies summary string. For a two-parameter read tool, nothing an agent needs in order to call it or interpret the result is missing.

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% and both parameters are documented inline, so baseline 3 applies. The description adds context the schema lacks — that a larger limit pages further back and takes longer — but gives no guidance on the default of 50 vs. the 500 maximum.

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 (read top-level messages of a space or DM) plus scope qualifiers (most recent, oldest first, top-level only). It explicitly separates itself from read_thread for threaded replies, so an agent can choose without opening either schema.

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?

Names the alternative explicitly — '"3 replies..."; read those with read_thread' — and gives the cost trade-off for raising the limit ('scroll back through history and take longer'). The top-level-only scope plus the named sibling covers both when-to-use and when to go elsewhere.

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