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

With no annotations, the description must carry the safety profile, and it does disclose mutation semantics: keys merge rather than replace, and null deletes settings. That is meaningful behavioral context. It omits other traits an agent would want: that this is an irreversibly mutating live-mock operation, whether omitted fields in a routes entry are preserved or reset, and any auth requirement, and it also partially repeats the merge note already present in the patch schema.

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, zero filler. The scope enumeration is front-loaded and the merge rule follows as the one non-obvious caveat, which is exactly the right ordering.

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 schema is rich and nested, so most parameter detail is covered, and the description correctly complements it with merge semantics. But for an unannotated mutation tool with no output schema, it says nothing about what is returned, what happens on a non-existent slug, or the owner-token path, leaving real gaps in the overall picture.

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 nested patch fields, ranges, and null-vs-absent semantics are already documented in the schema. The description's field list mirrors those keys without adding syntax or format detail (e.g., route identifier form, scenario bundle shape) beyond what the schema states. Baseline 3 applies.

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?

States a specific verb ('Change') and resource ('a mock's behaviour') and then enumerates the exact knobs affected: status, latency, jitter, error rate, persistent writes, per-route status/bodies/rules. That is far more specific than the name alone. It stops short of naming sibling tools (set_response, add_rule, reset_state), so the boundary with those is left implicit.

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 merge semantics sentence ('missing keys are kept, null clears') is a genuine usage instruction for partial updates and hints at how to clear a setting. However, there is no statement about when to prefer this over add_rule for rules or set_response for bodies, nor any prerequisite note about needing an owner token or a pre-existing mock.

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