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

No annotations are provided, so the description carries the full burden. The "(POST /pin)" fragment weakly implies a mutation, but nothing is said about whether the pin persists, is idempotent, requires prior checkpoint creation, or what happens if the pin already exists.

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?

It is a single front-loaded sentence with zero filler, which is structurally clean. But the brevity is under-specification rather than economy — the one sentence does not carry enough information for a 3-required-parameter mutation.

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?

No annotations, no output schema, no parameter documentation, and no explanation of the pinning domain concept. For a three-parameter write operation with a jargon-heavy name, this is far short of what an agent needs to invoke 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?

All three parameters (run_id, checkpoint_ns, discovery_pin) have 0% schema description coverage and the description mentions none of them. Names like discovery_pin and checkpoint_ns are ambiguous — is the pin a digest string, an ID, or a reference? Nothing here compensates.

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 gives a verb ("Pin") and an object ("checkpoint discovery digest"), plus an endpoint hint, so the general shape is inferable. However, "pin a digest" is opaque domain jargon and nothing distinguishes this from siblings like resume_verdict or resume_audit_journal — an agent cannot tell what pinning accomplishes or when it applies.

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?

There is no statement of when to call this tool, no preconditions, and no reference to the four sibling tools despite an obviously overlapping resume_* family. The agent must guess whether pinning is a prerequisite for resume_verdict or an alternative to resume_audit_journal.

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