save_attachment

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

Annotations already declare this is a non-destructive write (readOnlyHint=false, destructiveHint=false), so the bar is lower, yet the description still adds real behavior: the exact destination folder and the never-overwrites guarantee, which explains why idempotentHint is false — each call produces a new file. It does not mention whether the folder is created if missing or what happens on filename collisions.

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, front-loaded with the action and destination, with the no-overwrite constraint and return value following. Nothing is wasted.

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?

Output schema exists, so the return value need not be described (though it helpfully is). The main remaining gap is that max_chars implies text extraction, yet the description never explains that saved content may be truncated by that parameter, which matters for an agent handling large attachments.

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 id, index, and max_chars are already documented in the schema. The description adds no parameter-level meaning beyond that, which is acceptable at full coverage but not enriching.

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 (save an attachment) plus the destination (the user's Timbre attachments folder) and a key side-effect (never overwrites). It clearly differs from the sibling read_attachment, which only reads content, though it never names that sibling explicitly.

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?

Usage is implied: use this when you want the attachment materialized on disk rather than just read. There is no explicit statement of when to prefer save_attachment over read_attachment, nor any prerequisite such as obtaining the index from read_mail (that only appears in the schema).

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