Read Media File

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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the base64 encoding, MIME type inclusion, the content-type branching (image/audio vs embedded resource), and the allowed-directory restriction.

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 core purpose and return behavior front-loaded, followed by the branching detail and the directory constraint. No filler, though the return-format sentence is longer than strictly necessary given an output schema exists.

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 single-parameter read tool with an output schema present, the description covers purpose, output shape, and access constraints, so an agent has enough to invoke it correctly. The only real gap is path format semantics, which the empty schema description leaves undocumented.

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% and the single 'path' parameter carries no description, so the description is the only source of parameter meaning. It says nothing about path format (absolute vs relative) or resolution rules. With only one self-evident parameter, this is adequate but not compensating for the coverage gap.

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 gives a specific verb and resource ('Read a file') plus the distinctive output form ('base64-encoded content block with its MIME type'), which separates it from read_text_file. It does not explicitly name a sibling to contrast with, so it falls short of a 5.

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 by the media-oriented return behavior, and the constraint 'Only works within allowed directories' gives a boundary condition. However, it never states when to prefer this over read_file, read_text_file, or read_multiple_files, leaving the routing decision to inference.

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