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

With no annotations, the description carries the burden of disclosing behavior. It explicitly reveals that the tool is session-gated, that Hodor bypasses this, and that guardian rules always apply, which is meaningful access-control behavior beyond the schema. It does not elaborate on what 'guardian rules' entails or the response format, but for a simple getter it provides solid transparency.

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 sentences, front-loaded with the core action and identifier, followed by the auth nuance. Every sentence earns its place with no filler.

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?

For a two-parameter getter with no output schema, it gives the lookup key, auth rule, and an exception. It does not describe errors or the exact response shape, but the phrase 'full prompt' already signals the return value; remaining gaps are minor.

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%: session_token already has a detailed schema description, and the tool description mostly restates that. The only addition for slug is that lookup happens 'by slug', compensating somewhat for the schema's bare string type. Overall the description adds modest meaning but does not fully enrich parameters.

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 opens with a specific action and target ('Return one persona's full prompt by slug'), which clearly identifies the resource and lookup key. This distinguishes it from siblings like get_persona_journal or list_personas because it specifies 'full prompt' and 'by slug'.

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?

It explains the authorization context: the tool is session-gated, has a Hodor exception, and tells callers when to pass session_token instead of an Authorization header. It does not name alternative tools or state when not to use it, so it falls just short of 5.

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