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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds the key behavioral fact that this tool does not subscribe (i.e., it only discovers), and that it returns feedUrl values to be used with follow_feeds. It does not contradict annotations and adds useful context beyond the safety profile.

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 compact: two sentences and an example, with no wasted words. It front-loads the primary purpose, then gives usage guidance and a behavioral note, followed by a helpful example. Every sentence 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?

The tool has an output schema, so return format is covered. The description covers purpose, usage, alternatives, and an example. It does not mention pagination or error handling, but for a simple discovery tool with read-only annotations, that is acceptable. The description is complete enough for an agent to call it correctly.

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 50% (only mode is described in the schema). The description compensates by explaining the two modes ('feeds' searches by topic; 'site' discovers what a specific URL publishes) and provides a concrete example with both query and mode, clarifying that query is a URL in site mode. This adds meaningful semantics beyond the bare schema.

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 states a specific action ('Find public feeds by topic or find a site's published feeds') and clearly distinguishes itself from sibling tools by naming search_feeds (for language/ranking/source-type controls) and follow_feeds (for subscribing). The phrase 'compact Developer API discovery adapter' further sets expectations. This is a clear, specific purpose that an agent can use to decide whether to invoke this tool.

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 description explicitly tells the agent when to use this tool vs alternatives: 'use search_feeds for language, ranking, and source-type controls' and 'Discovery does not subscribe; pass result feedUrl values to follow_feeds.' This gives clear conditions and alternatives, so the agent knows when to choose this tool and what to do with its output.

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