Read a file

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the description adds value by disclosing the 8 MB ceiling on returned text and by warning that file content is untrusted exported data whose embedded instructions must not be followed. That injection warning is genuinely important behavioral context for an agent reading arbitrary file text. It does not say whether oversized files error or truncate, which is the one missing detail.

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 sentences, both front-loaded: the operation and size limit come first, the safety directive second. Nothing is redundant or padded.

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 one-parameter read tool with full annotation coverage and a complete schema, the description covers the only remaining needs: the size cap and how to treat the returned content. Return shape is stated, so the absence of an output schema is not a gap.

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?

With a single parameter at 100% schema coverage, the schema already documents that uri must be exactly what list_files returned. The description restates that requirement rather than adding new semantics such as uri format or error behavior for an unknown uri. Baseline 3 applies.

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 ("Reads one file") plus its scope (files this server shares) and its exact return (whole text, max 8 MB). It is clearly distinguished from the sibling list_files, whose output is named as the input source.

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 phrase "by the uri list_files gave" explicitly chains this tool after list_files, telling the agent the correct call sequence. There is no statement of when not to use it or of the error path for a bad uri, so it stops short of a full 5.

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