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

Annotations already establish readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable context about V2 message identity being contextual to the chat and provider uniqueness guarantees, plus explicit anti-patterns like 'Never pass: person name, user_id, message_id.' It does not mention return format, but this is a read operation whose safety profile is already covered by 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?

The first sentence is excellent and front-loaded, but the rest is verbose and somewhat repetitive: 'Exact provider chat/conversation ID' and 'Exact message id inside a specific chat' are duplicated from the schema, and the tail about 'for mutation tools' is tangential to a get operation. Labeled Chat ID and Message ID sections help structure, but several sentences could be tightened.

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 gives complete ID-provenance guidance, a resolution workflow, and safety annotations, so an agent can invoke the tool correctly. It lacks an explicit statement of what the response contains and relies partly on schema text for account_id guidance, but this is a minor gap for a straightforward get operation with no output schema.

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 baseline is 3. The description adds meaningful parameter semantics beyond the schema by explaining how to obtain the IDs, why chat_id and message_id must stay paired, and what values must never be passed. It does not cover account_id in the main description, but the schema fully documents that parameter.

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 opens with 'Get one exact message,' a specific verb and resource, and immediately clarifies the singular scope. It differentiates from message listing and mutation siblings by emphasizing that both chat_id and message_id are required and context-bound.

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 gives explicit workflow guidance: 'If starting from a person/topic, resolve chat first, list messages, then reuse both IDs.' It also tells the agent how to obtain each ID from provider listings and what never to pass, though it does not explicitly name alternative sibling tools to prefer in other situations.

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