MCP Action Firewall

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

Annotations are absent, so description carries full burden. It discloses the session-scoped nature ('during the current session') and return alternatives. Missing: error conditions (invalid URLs, compression failures), persistence guarantees, and idempotency characteristics expected for a mutation tool.

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 well-structured sentences with zero waste. Front-loaded with core action (compression), followed by return behavior clarification. Every clause earns its place.

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?

With no output schema, description adequately explains the polymorphic return (resource vs resourceLink). Given 100% input schema coverage, explanation of the gzip operation and session scoping provides sufficient context for moderate complexity, though error scenarios remain 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 has 100% coverage establishing baseline 3. Description adds value by emphasizing 'single file' cardinality constraint and explaining how outputType affects downstream behavior ('allowing it to be downloaded in a subsequent request'), connecting the enum parameter to concrete usage implications.

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 uses specific verb 'compresses' with resource 'single file' and method 'gzip compression'. It clearly distinguishes from sibling 'get-resource-links' and 'get-resource-reference' by emphasizing this creates new compressed content rather than retrieving existing resources.

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?

Explains what each outputType option does (resourceLink for deferred download, resource for immediate data), implying when to use each. However, lacks explicit guidance like 'use resourceLink for large files' or contrast with alternative tools.

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