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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond the annotations: it clarifies the tool only reads conversations the user started, and it discloses the '[free, no key]' property, which is useful operational context not present in the schema or annotations. It does not describe pagination or error behavior, but for a read-only conversation fetch, the added context is solid.

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 a single, front-loaded sentence that states the action, the resource, and the return contents, followed by a short parenthetical about cost/auth. Every word earns its place; there is no fluff or repetition of schema details.

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 read-only tool with 100% schema coverage and no output schema, the description is nearly complete. It tells the agent what it will get (state, messages, reply count) and the access requirement (free, no key). It does not explain the relationship between the three parameters (e.g., which to prefer), but the schema already documents that, so the description does not need to repeat it. A small gap is the lack of any note about what happens if the conversation is not found, but that is minor.

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 schema already documents all three parameters. The description adds the 'two-way conversation thread you started' context and the '[free, no key]' note, but it does not add meaning about how the parameters relate (e.g., reference requires business_number, conversation_id is preferred). The schema already covers those details, so the baseline 3 is appropriate.

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 ('Read'), a specific resource ('a two-way conversation thread you started'), and enumerates exactly what is returned: state, every message exchanged, and reply count. It also distinguishes itself from siblings by scoping to conversations the user started, which is not evident from the tool name alone.

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 context for when to use the tool: to read a two-way conversation thread you started. It does not explicitly name alternatives or exclusions, but the sibling list includes get_status, get_outcome, and check_compliance, and the description's focus on 'conversation thread' and 'messages' makes the usage context clear enough. It lacks an explicit 'use X instead when...' statement, so it falls short of a 5.

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