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

Despite read-only annotations, the description adds substantial behavioral context: history is scoped to this chat only, messages are not execution proof or permission, they must not set reply language, empty journals do not rule out outside changes, and live account data should be checked before decisions. These are exactly the caveats an agent needs before relying on recalled conversation data.

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 description is front-loaded with the core scope and mode behavior, and most sentences carry operational value. It is dense and includes some platform-level meta guidance about MCP arguments and credits, which slightly dilutes conciseness but does not obscure the key instructions.

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?

For a multi-mode recall tool with no output schema, the description covers scope, mode selection, pagination, and important interpretive caveats well. It does not fully describe the returned data shape, but it gives enough behavioral and usage context for an agent to call the tool 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?

The description explains the key nested parameters that the schema leaves undocumented: mode behavior, query usage, beforePosition pagination, turnId plus part for single messages, and offset pagination for actions. It adds real meaning beyond the schema, though accountIds, userStatement, and idempotencyKey are left to their schema descriptions.

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 states a specific verb and resource: reading this chat's durable history, explicitly excluding other chats and workspaces. It distinguishes the three modes (messages, message, actions) so an agent can understand the tool's scope without opening the 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?

The description gives clear usage instructions per mode, including when to omit query, how to paginate, and how to broaden searches when no matches are found. It also warns not to treat historical messages as live or authoritative, but it does not explicitly name sibling alternatives such as actions_recent.

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