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

With no annotations, the description must carry the safety/behavior burden. 'Fetch' clearly indicates a read operation and 'full card' indicates the response scope, but it does not disclose error behavior, required authorization, or what fields a 'card' contains.

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?

One short sentence front-loads the action and object, with no filler or repeated schema information. It earns its place by adding the 'registered' and 'full card' context.

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 is simple (one required parameter, no output schema), but the absence of annotations and output schema means the description should say more about what a 'full card' contains and what happens when no match is found. It is adequate but leaves those gaps.

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?

The schema has 0% property-description coverage, so the description must define the only parameter. It says 'slug or numeric id,' but the schema requires a string `slug`, so the accepted format is ambiguous and potentially misleading for an agent deciding what value to pass.

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 uses a specific verb ('Fetch'), identifies the resource ('one registered agent'), and signals the returned artifact ('full card'), which distinguishes it from the broader discover/list/search siblings. However, the claim 'by slug or numeric id' conflicts with a schema that only defines a string `slug`, introducing ambiguity and keeping it from 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?

Use is implied: call this when you need a single agent's full card by identifier. The description gives no explicit when-not-to-use guidance or alternatives, though the singular 'one' hints at the distinction from discovery tools.

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