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

With no annotations provided, the description fully carries the burden of behavioral disclosure. It transparently states the lock is 'SINGLE INSTANCE ONLY,' lives in memory, is empty after every deploy, and is not safe across replicas. It also discloses the TTL limit (300s) and the default (60s). This is comprehensive for a mutex tool with no structured annotation support.

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 concise and front-loaded with the core purpose, then expands on constraints and alternatives. It is not overly verbose; each sentence adds value, though the naming guidance could be slightly tightened. The structure logically flows from function to limitations to usage alternative.

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 description is complete for an agent to invoke the tool correctly. It covers the lock lifecycle, TTL, naming requirements, single-instance limitation, and the alternative tool. There is no output schema, but the description sufficiently clarifies behavior, and the schema documents parameters. Nothing critical is missing.

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 description coverage is 100%, so the baseline is 3. The description adds meaningful context beyond the schema: it explains why the key should be random (to avoid squatting) and notes the TTL default, which reinforces the schema's default mention. It does not introduce new parameter information but enriches understanding of the parameters' intent.

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 clearly states the tool's function: 'Advisory mutex across agents. Acquire a named lock for up to 300s, or release one.' It identifies the specific verb (acquire/release), resource (named lock), and duration. It also distinguishes itself from the sibling 'lease' by contrasting use cases, making it easy for an agent to select the right 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 provides explicit when-to-use and when-not-to-use guidance. It states 'Use "lease" instead for anything that must outlive a restart,' directly routing the agent to an alternative. It also explains the naming requirement (random, at least 24 characters) and why short names are risky, giving actionable criteria for invocation.

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