lookup_mime_types

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

Annotations provide readOnlyHint=true, indicating a read operation. The description adds no additional behavioral info (e.g., whether it uses a local database, online lookup, error handling for invalid inputs, or result format). It does not go beyond what annotations already convey.

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?

The description is a single, front-loaded sentence with no filler. However, it could be slightly expanded to clarify bidirectional functionality without losing conciseness.

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?

Given the tool's simplicity and full schema coverage, the description is minimally adequate. However, it does not mention the output format (MIME types or extensions), which is not covered by an output schema. Sibling tools like 'identify_file_type' offer related functionality, but no comparison is provided. Minor gaps in completeness.

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 both parameters are fully documented in the schema. The description adds no extra meaning beyond the schema, such as clarifying the relationship between input and lookupType or expected formats (e.g., dots in extensions). Baseline 3 applies due to high schema coverage.

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?

Description states specific verb+resource ('Look up MIME types for file extensions'), but omits that it also supports reverse lookup (MIME to extension) as shown in the schema's lookupType enum. This makes it slightly narrower than actual functionality, though still clear for the primary use case.

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?

No guidance on when to use this tool vs alternatives (e.g., lookup_http_status, lookup_port_numbers, or identify_file_type). The description lacks any context about ideal scenarios or exclusions, leaving the agent without direction for tool selection.

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