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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered; the description usefully adds that the return is a static document with a fixed set of sections. It also clarifies a behavioral boundary agents would otherwise guess at: geometry is handled by the engine with real fonts, so PBL text does not need to encode measurements.

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?

Front-loaded with the return payload, then the usage trigger, then supporting context about the language. Four short sentences with little waste, though the closing sentence about font measurement and geometry is only tangentially necessary for deciding to call the tool.

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 zero parameters, no output schema and annotations covering the safety profile, the description carries the remaining burden well: it says what comes back, what the language is, and when to read it. An agent has everything needed to decide to call it.

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 tool takes no parameters (empty schema), so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly implies a single fixed output with no arguments to tune.

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 ("Return") and names the resource precisely (the complete Picorn Blueprint Language spec), then enumerates its contents: syntax, design rules, a full example and repair patch rules. That is well beyond a tautology. It stops short of a 5 because it does not differentiate itself from the sibling picorn_blueprint_examples, which plausibly overlaps with the "full example" content claimed here.

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?

"Read it once before writing PBL" gives an explicit trigger condition tied to a downstream activity, which is exactly the guidance an agent needs for a spec-fetch tool. It does not, however, name alternatives (e.g. picorn_blueprint_examples for examples, picorn_capabilities for capability discovery) or state when this tool is unnecessary.

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