get_object_textRead text-based content from an S3 object, capping output at max_bytes (default 256KiB) to prevent large binaries from entering agent context.
[READ] S3 GetObject for text-ish content. Caps at max_bytes (default 256KiB) to avoid dumping large binaries into the agent context. Official API Usage getObject.
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes | ||
| bucket | Yes | ||
| max_bytes | No |
Changes observed during successful MCP inspections.
v0.5.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnly and openWorld, so the bar is lower. The description adds genuinely useful behavior: a default cap of 256KiB and the rationale of protecting agent context from large binaries. It stops short of saying what happens on truncation.
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?
Three tight sentences with the [READ] marker front-loaded and the cap rationale stated early. Nothing is wasted, though the trailing 'Official API Usage getObject' is low-value filler.
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?
No output schema, so return values need not be explained. For a read tool whose safety profile is covered by annotations, the definition is adequate, but it omits the key edge case: whether content over max_bytes is truncated or errors, and whether binary content is rejected.
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 coverage is 0%, so the description should carry the load. It documents max_bytes only partially — the 256KiB default is added value absent from the schema — but leaves bucket/key and the exact truncation semantics of max_bytes unexplained.
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 action and resource: S3 GetObject returning text-ish content. The 'text' qualifier and cap behavior distinguish it from a generic object fetch and from the write-side sibling put_object_text, though no sibling is named directly.
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 text-ish/binary-avoidance framing implies when to use it, but it never names an alternative (e.g., a raw binary get) or states exclusions explicitly. Usage is inferable rather than prescribed.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.