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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true; the description usefully corroborates the open-world nature by naming NCBI Batch CD-Search as the upstream service. It adds nothing on latency, remote service availability, or the fact that in auto/prec mode no search is performed and db/evalue/maxhit are silently ignored — behaviorally important context that the agent only finds in the parameter descriptions.

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?

One front-loaded sentence: verb, substrate, target database, upstream service. No filler, though the parenthetical collection list is long relative to the small amount of instruction offered.

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 an output schema, 100% parameter coverage and non-destructive read annotations, the definition is technically usable, but for an 11-parameter tool with a DNA/protein duality and three search modes, the one-sentence description leaves the agent to reverse-engineer the calling contract from the schema and gives no help against three similarly named siblings. Adequate minimum, but with clear gaps.

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 schema already documents all 11 parameters including the mode enums and the nested _subject/_files objects. The description contributes a little by naming the concrete db collections (Pfam, SMART, COG, KOG, PRK, TIGR), which concretizes the opaque 'PSSM collection' wording in the schema, but nothing else beyond the schema.

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 (RPS-BLAST) plus a specific resource (NCBI CDD and its enumerated member collections), which is more informative than a generic 'search domains'. It does not, however, distinguish itself from near-identical siblings such as rps_blast_smart, rpstblastn_smart and scan_protein_domains, so an agent cannot tell from the description alone which to pick.

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 when-to-use guidance at all: nothing about when to prefer this over rps_blast_smart or rpstblastn_smart, no mention of the auto/prec/live trade-off that governs whether a search actually runs, and no note that dna can be supplied instead of protein. Usage must be inferred entirely from the schema.

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