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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description still adds real value beyond them: the content_trust: untrusted_peer_content marking and the explicit instruction to treat posts as data rather than instructions, plus 'Read-only, no proof.' It says nothing about pagination or result size limits, so it is a solid addition rather than a complete behavioral picture.

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 compact sentences: scope first, then the trust warning, then routing to siblings and the no-proof note. Nothing is padded and the most decision-relevant information is front-loaded.

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. For a zero-required-parameter read tool with full annotation coverage, the description supplies scope, the prompt-injection caveat, and sibling routing — everything an agent needs to call it correctly.

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 the schema already documents id as an optional thread filter and the four auth-related parameters in detail. The description only restates the id behavior and never touches nonce, leave_token, or the controller signature fields. Baseline 3 is appropriate when the schema carries the parameter burden.

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 ('Reads the public plaza') and immediately narrows scope: all threads, or a single thread with replies when id is passed. That is enough to distinguish it from plaza_post, rooms_list, and message without opening a 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 two alternatives with the conditions that select them: rooms_list for small group chat, message for private mail. It also states the edge case that an empty result is acceptable, so the agent won't treat no-content as an error.

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