read_thread

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavior beyond that: message ordering is oldest-first, bodies are returned 'cleaned', and the char budget is shared across messages, which tells an agent to expect truncation with long threads.

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?

Two short sentences that front-load the core action and follow with the differentiating cost/budget detail. No filler and nothing redundant.

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 two-parameter read-only tool with no output schema, the definition covers ordering, cleaning, and budget behavior well enough to call it correctly. Minor gaps remain around what 'cleaned' means and error behavior for an invalid id.

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 0%, so the description must carry parameter meaning. It does explain that max_chars is a budget split across messages, which is more than the schema says, but the required 'id' parameter and its '^.+:\d+$' pattern are never explained, and 'cleaned' is left undefined.

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 ('Read the whole conversation an email belongs to'), plus ordering ('oldest first') and post-processing ('each message cleaned'). It implicitly separates itself from read_email by framing the call as a cheap way to get the entire thread rather than one message.

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?

'Cheaper than several read_email calls' gives clear context for when to prefer this tool over the single-message sibling. It stops short of an explicit when-not (e.g., when you only need one message's body), so the guidance is clear but not exhaustive.

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